From 9b9fa18992cbfa6547146834eeb5b4e0e2fb6ae3 Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Tue, 23 Jun 2026 14:02:55 -0700
Subject: [PATCH 1/9] =?UTF-8?q?the=20median=20diff=20col=20has=20been=20re?=
 =?UTF-8?q?placed=20with=20a=20mode=20=CE=94=20col?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../CompareResults/ResultsTable.test.tsx      | 256 +++++++--------
 .../CompareResults/RevisionRow.test.tsx       |  71 ----
 .../SubtestsResultsView.test.tsx              | 102 +++---
 .../SubtestsRevisionRow.test.tsx              |  60 ----
 .../OverTimeResultsView.test.tsx.snap         |  52 +--
 .../__snapshots__/ResultsTable.test.tsx.snap  | 178 ++++------
 .../__snapshots__/ResultsView.test.tsx.snap   |  52 +--
 .../SubtestsResultsView.test.tsx.snap         | 310 ++++++------------
 src/common/constants.ts                       |   4 +-
 src/common/testVersions/mannWhitney.tsx       | 117 +++----
 src/components/CompareResults/loader.ts       |  23 ++
 .../CompareResults/overTimeLoader.ts          |  12 +
 .../CompareResults/subtestsLoader.ts          |  13 +-
 .../CompareResults/subtestsOverTimeLoader.tsx |  11 +-
 src/types/state.ts                            |   6 +
 src/utils/kdeAnalysis.ts                      |  60 ++++
 16 files changed, 562 insertions(+), 765 deletions(-)

diff --git a/src/__tests__/CompareResults/ResultsTable.test.tsx b/src/__tests__/CompareResults/ResultsTable.test.tsx
index c663ada1d..57e9f4930 100644
--- a/src/__tests__/CompareResults/ResultsTable.test.tsx
+++ b/src/__tests__/CompareResults/ResultsTable.test.tsx
@@ -85,7 +85,7 @@ function summarizeVisibleRows(testVersion?: TestVersion) {
           testVersion === 'mann-whitney-u'
             ? [
                 '.platform span',
-                '.median-diff',
+                '.mode-delta',
                 '.status',
                 '.delta',
                 '.significance',
@@ -722,9 +722,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  rev: devilrabbit',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(screen.getByRole('rowgroup')).toMatchSnapshot();
   });
@@ -748,12 +748,12 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await screen.findByText('a11yr');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
 
     expect(summarizeTableFiltersFromUrl()).toEqual({});
@@ -762,9 +762,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Windows/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'linux', 'android', 'ios'],
@@ -775,12 +775,12 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Windows/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
@@ -788,8 +788,8 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Linux/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios'],
@@ -798,9 +798,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Linux/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios', 'linux'],
@@ -809,22 +809,22 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', 'Select all values');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
     await clickMenuItem(user, 'Platform', /macOS/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['windows', 'linux', 'android', 'ios'],
@@ -833,9 +833,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Android/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['windows', 'linux', 'ios'],
@@ -844,7 +844,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Select only.*Android/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Android, -, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['android'],
@@ -883,10 +883,10 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await screen.findByText('a11yr');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
@@ -894,8 +894,8 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /No changes/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['improvement', 'regression'],
@@ -904,7 +904,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Improvement/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -914,9 +914,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['none', 'improvement'],
@@ -925,17 +925,17 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
     await clickMenuItem(user, 'Status', /Select only.*Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -944,7 +944,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Select only.*Improvement/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['improvement'],
@@ -961,7 +961,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
 
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
     ]);
     const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
     expect(await summarizeTableFiltersFromCheckboxes(user)).toEqual({
@@ -997,26 +997,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
       '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
+      '  - Windows 10, -, , 1.2, , 49.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
       '  - Windows 10, -, , 2, , 98.00 %',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
+      '  - Windows 10, -, , 2, , 48.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
       '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
+      '  - Windows 10, -, , 0.8, , 49.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(deltaButton).toMatchSnapshot();
@@ -1028,25 +1028,25 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
+      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
+      '  - Windows 10, -, , 2, , 48.00 %',
       '  - Windows 10, -, , 2, , 98.00 %',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
+      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, -, , 1.2, , 49.00 %',
       '  - Windows 10, -, , 1.2, , 99.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
+      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, -, , 0.8, , 49.00 %',
       '  - Windows 10, -, , 0.8, , 99.00 %',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
     ]);
     // It should have the "ascending" SVG.
@@ -1062,26 +1062,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
       '  - Windows 10, -, , 2, , 98.00 %',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
+      '  - Windows 10, -, , 2, , 48.00 %',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
       '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
+      '  - Windows 10, -, , 1.2, , 49.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
       '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
+      '  - Windows 10, -, , 0.8, , 49.00 %',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(significanceButton).toMatchSnapshot();
@@ -1093,26 +1093,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
+      '  - Windows 10, -, , 0.8, , 49.00 %',
       '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
+      '  - Windows 10, -, , 1.2, , 49.00 %',
       '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
+      '  - Windows 10, -, , 2, , 48.00 %',
       '  - Windows 10, -, , 2, , 98.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(significanceButton).toMatchSnapshot();
@@ -1128,25 +1128,25 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
       '  - Windows 10, -, , -, , 100.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
       '  rev: tictactoe',
       '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
+      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, -, , 0.8, , 49.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
       '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
+      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, -, , 1.2, , 49.00 %',
       '  rev: tictactoe',
       '  - Windows 10, -, , 2, , 98.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
+      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
+      '  - Windows 10, -, , 2, , 48.00 %',
     ]);
 
     expect(effectSizeButton).toMatchSnapshot();
@@ -1158,45 +1158,45 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
       '  - Windows 10, -, , -, , 100.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %',
+      '  - Windows 10, -, , 0.8, , 49.00 %',
+      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
       '  - Windows 10, -, , 0.8, , 99.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %',
+      '  - Windows 10, -, , 1.2, , 49.00 %',
+      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
       '  - Windows 10, -, , 1.2, , 99.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %',
+      '  - Windows 10, -, , 2, , 48.00 %',
+      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
       '  - Windows 10, -, , 2, , 98.00 %',
     ]);
     expect(effectSizeButton).toMatchSnapshot();
     // It should be persisted in the URL
     expectParameterToHaveValue('sort', 'effects|asc');
 
-    // Sort by MD(%) descending
-    const medianDiffButton = screen.getByRole('button', {
-      name: /MD \(%\).*sort/,
+    // Sort by Mode Δ (%) descending
+    const modeDeltaButton = screen.getByRole('button', {
+      name: /Mode .*sort/,
     });
-    await user.click(medianDiffButton);
+    await user.click(modeDeltaButton);
     expect(summarizeVisibleRows('mann-whitney-u')).toMatchSnapshot();
-    expect(medianDiffButton).toMatchSnapshot();
-    expectParameterToHaveValue('sort', 'median-diff|desc');
+    expect(modeDeltaButton).toMatchSnapshot();
+    expectParameterToHaveValue('sort', 'mode-delta|desc');
 
-    // Sort by MD(%) ascending
-    await user.click(medianDiffButton);
+    // Sort by Mode Δ (%) ascending
+    await user.click(modeDeltaButton);
     expect(summarizeVisibleRows('mann-whitney-u')).toMatchSnapshot();
-    expect(medianDiffButton).toMatchSnapshot();
-    expectParameterToHaveValue('sort', 'median-diff|asc');
+    expect(modeDeltaButton).toMatchSnapshot();
+    expectParameterToHaveValue('sort', 'mode-delta|asc');
   });
 
   it('should switch between Student-T and Mann-Whitney-U test versions', async () => {
diff --git a/src/__tests__/CompareResults/RevisionRow.test.tsx b/src/__tests__/CompareResults/RevisionRow.test.tsx
index ae86e4950..b33332cd3 100644
--- a/src/__tests__/CompareResults/RevisionRow.test.tsx
+++ b/src/__tests__/CompareResults/RevisionRow.test.tsx
@@ -4,7 +4,6 @@ import fetchMock from '@fetch-mock/jest';
 import userEvent from '@testing-library/user-event';
 
 import { compareView } from '../../common/constants';
-import { isDistributionNormal } from '../../common/testVersions/mannWhitney';
 import { loader } from '../../components/CompareResults/loader';
 import RevisionRow from '../../components/CompareResults/RevisionRow';
 import { useSubtestRegressionCount } from '../../hooks/useSubtestRegressionCount';
@@ -524,76 +523,6 @@ describe('Expanded row', () => {
 
     expect(writeTextMock).toHaveBeenCalledWith(baseRuns);
   });
-
-  describe('median diff column normality gating', () => {
-    const normalRuns = [5.1, 5.2, 4.9, 5.0, 5.05];
-    const tooFewRuns = [5.0];
-
-    function makeResult(
-      baseRuns: number[],
-      newRuns: number[],
-    ): MannWhitneyResultsItem {
-      const { testCompareMannWhitneyData } = getTestData();
-      return {
-        ...testCompareMannWhitneyData[0],
-        base_runs: baseRuns,
-        new_runs: newRuns,
-      };
-    }
-
-    it('shows dash when neither distribution is normal', async () => {
-      const result = makeResult(tooFewRuns, tooFewRuns);
-      expect(isDistributionNormal(result)).toBe(false);
-      renderWithRoute(
-        <RevisionRow
-          result={result}
-          view={compareView}
-          gridTemplateColumns='none'
-          replicates={false}
-          testVersion='mann-whitney-u'
-          expandAll={false}
-        />,
-      );
-      const roles = await screen.findAllByRole('cell');
-      expect(roles[4]).toHaveTextContent('-');
-    });
-
-    it('shows value with warning icon when only one distribution is normal', async () => {
-      const result = makeResult(normalRuns, tooFewRuns);
-      expect(isDistributionNormal(result)).toBe(true);
-      renderWithRoute(
-        <RevisionRow
-          result={result}
-          view={compareView}
-          gridTemplateColumns='none'
-          replicates={false}
-          testVersion='mann-whitney-u'
-          expandAll={false}
-        />,
-      );
-      const roles = await screen.findAllByRole('cell');
-      expect(roles[4]).not.toHaveTextContent('-');
-      expect(roles[4].querySelector('svg[role="img"]')).toBeTruthy();
-    });
-
-    it('shows value without warning icon when both distributions are normal', async () => {
-      const result = makeResult(normalRuns, normalRuns);
-      expect(isDistributionNormal(result)).toBe(true);
-      renderWithRoute(
-        <RevisionRow
-          result={result}
-          view={compareView}
-          gridTemplateColumns='none'
-          replicates={false}
-          testVersion='mann-whitney-u'
-          expandAll={false}
-        />,
-      );
-      const roles = await screen.findAllByRole('cell');
-      expect(roles[4]).not.toHaveTextContent('-');
-      expect(roles[4].querySelector('svg[role="img"]')).toBeFalsy();
-    });
-  });
 });
 
 describe('expandAll prop', () => {
diff --git a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
index 87e1b9081..aaf94410d 100644
--- a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
@@ -59,7 +59,7 @@ function summarizeVisibleRows(testVersion?: TestVersion) {
     }
     const rowClasses =
       testVersion === 'mann-whitney-u'
-        ? ['.median-diff', '.delta', '.significance', '.effects']
+        ? ['.mode-delta', '.delta', '.significance', '.effects']
         : ['.delta', '.confidence'];
     const rowString = rowClasses
       .map((selector) => row.querySelector(selector)?.textContent.trim())
@@ -527,11 +527,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting();
       // Initial view (alphabetical ordered, even if "sort by subtests" isn't specified
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
       ]);
 
       // Sort by Delta
@@ -542,11 +542,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort descending
       await user.click(deltaButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
       ]);
 
       // It should have the "descending" SVG.
@@ -557,11 +557,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort ascending
       await user.click(deltaButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'regression.html: 1.135 %, 0.12, , 25.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'regression.html: -, 0.12, , 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -574,11 +574,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       });
       await user.click(significanceButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'improvement.html: -, -0.05, , 50.00%',
       ]);
       // It should have the "no sort" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -590,11 +590,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort by Significance ascending
       await user.click(significanceButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
+        'browser.html: -, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'significance|asc');
 
@@ -604,11 +604,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       });
       await user.click(effectButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
+        'improvement.html: -, -0.05, , 50.00%',
       ]);
 
       // It should have the "descending" SVG.
@@ -619,11 +619,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort by Effect Size ascending
       await user.click(effectButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'browser.html: -, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'effects|asc');
     });
@@ -632,11 +632,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting({ extraParameters: 'sort=delta|asc' });
       await screen.findByText('dhtml.html');
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'regression.html: 1.135 %, 0.12, , 25.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'regression.html: -, 0.12, , 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -646,11 +646,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting({ extraParameters: 'sort=delta' });
       await screen.findByText('dhtml.html');
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -659,11 +659,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
     it('initializes the sort from the URL at load time for a descending sort', async () => {
       await setupForSorting({ extraParameters: 'sort=delta|desc' });
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: 1.135 %, 0.12, , 25.00%',
-        'improvement.html: 0.963 %, -0.05, , 50.00%',
-        'browser.html: 0.963 %, -0.04, -, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, , 60.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
+        'regression.html: -, 0.12, , 25.00%',
+        'improvement.html: -, -0.05, , 50.00%',
+        'browser.html: -, -0.04, -, 15.00%',
+        'dhtml.html: -, 0.02, , 60.00%',
+        'tablemutation.html: -, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
diff --git a/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx b/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
index d8941e030..c6ca89d23 100644
--- a/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
@@ -5,7 +5,6 @@ import userEvent from '@testing-library/user-event';
 
 import { loader } from '../../components/CompareResults/loader';
 import SubtestsRevisionRow from '../../components/CompareResults/SubtestsResults/SubtestsRevisionRow';
-import { MannWhitneyResultsItem } from '../../types/state';
 import getTestData from '../utils/fixtures';
 import { screen, renderWithRouter } from '../utils/test-utils';
 
@@ -235,63 +234,4 @@ describe('SubtestsRevisionRow Component', () => {
     expect(status1).toHaveTextContent('Improvement');
     expect(status1).toHaveClass('status-hint-improvement');
   });
-
-  describe('median diff column normality gating', () => {
-    const normalRuns = [5.1, 5.2, 4.9, 5.0, 5.05];
-    const tooFewRuns = [5.0];
-    const mockGridTemplateColumns = '1fr 1fr 1fr 1fr 1fr 1fr 1fr 1fr';
-
-    function makeResult(
-      baseRuns: number[],
-      newRuns: number[],
-    ): MannWhitneyResultsItem {
-      const { subtestsMannWhitneyResult } = getTestData();
-      return {
-        ...subtestsMannWhitneyResult[0],
-        base_runs: baseRuns,
-        new_runs: newRuns,
-      };
-    }
-
-    it('shows dash when neither distribution is normal', async () => {
-      renderWithRoute(
-        <SubtestsRevisionRow
-          result={makeResult(tooFewRuns, tooFewRuns)}
-          gridTemplateColumns={mockGridTemplateColumns}
-          replicates={false}
-          testVersion='mann-whitney-u'
-        />,
-      );
-      const roles = await screen.findAllByRole('cell');
-      expect(roles[4]).toHaveTextContent('-');
-    });
-
-    it('shows value with warning icon when only one distribution is normal', async () => {
-      renderWithRoute(
-        <SubtestsRevisionRow
-          result={makeResult(normalRuns, tooFewRuns)}
-          gridTemplateColumns={mockGridTemplateColumns}
-          replicates={false}
-          testVersion='mann-whitney-u'
-        />,
-      );
-      const roles = await screen.findAllByRole('cell');
-      expect(roles[4]).not.toHaveTextContent('-');
-      expect(roles[4].querySelector('svg[role="img"]')).toBeTruthy();
-    });
-
-    it('shows value without warning icon when both distributions are normal', async () => {
-      renderWithRoute(
-        <SubtestsRevisionRow
-          result={makeResult(normalRuns, normalRuns)}
-          gridTemplateColumns={mockGridTemplateColumns}
-          replicates={false}
-          testVersion='mann-whitney-u'
-        />,
-      );
-      const roles = await screen.findAllByRole('cell');
-      expect(roles[4]).not.toHaveTextContent('-');
-      expect(roles[4].querySelector('svg[role="img"]')).toBeFalsy();
-    });
-  });
 });
diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index dbd059e14..8d866e9f2 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -346,7 +346,7 @@ exports[`Results View The table should match snapshot and other elements should
       </div>
     </div>
     <div
-      class="fdtnfac f1l733lh"
+      class="f1ozcnof f1l733lh"
       data-testid="table-header"
       role="row"
     >
@@ -413,16 +413,16 @@ exports[`Results View The table should match snapshot and other elements should
         </span>
       </div>
       <div
-        class="cell median-diff-header"
+        class="cell mode-delta-header"
         role="columnheader"
       >
         <span
-          aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
           <button
-            aria-label="MD (%) (Click to sort by this column)"
+            aria-label="Mode Δ (%) (Click to sort by this column)"
             class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
             tabindex="0"
             type="button"
@@ -438,10 +438,10 @@ exports[`Results View The table should match snapshot and other elements should
                 d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
               />
               <title>
-                Not sorted by MD (%)
+                Not sorted by Mode Δ (%)
               </title>
             </svg>
-            MD (%)
+            Mode Δ (%)
           </button>
         </span>
       </div>
@@ -742,7 +742,7 @@ exports[`Results View The table should match snapshot and other elements should
               class="revision-block fw0pvlu"
             >
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -791,14 +791,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -940,7 +936,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -990,14 +986,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -1139,7 +1131,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -1189,14 +1181,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -1338,7 +1326,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -1388,14 +1376,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index 95b362d3d..286a50900 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1319,7 +1319,7 @@ exports[`Results Table Should match snapshot 1`] = `
                   </div>
                 </div>
                 <div
-                  class="fdtnfac f1l733lh"
+                  class="f1ozcnof f1l733lh"
                   data-testid="table-header"
                   role="row"
                 >
@@ -1386,16 +1386,16 @@ exports[`Results Table Should match snapshot 1`] = `
                     </span>
                   </div>
                   <div
-                    class="cell median-diff-header"
+                    class="cell mode-delta-header"
                     role="columnheader"
                   >
                     <span
-                      aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
                       <button
-                        aria-label="MD (%) (Click to sort by this column)"
+                        aria-label="Mode Δ (%) (Click to sort by this column)"
                         class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
                         tabindex="0"
                         type="button"
@@ -1411,10 +1411,10 @@ exports[`Results Table Should match snapshot 1`] = `
                             d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
                           />
                           <title>
-                            Not sorted by MD (%)
+                            Not sorted by Mode Δ (%)
                           </title>
                         </svg>
-                        MD (%)
+                        Mode Δ (%)
                       </button>
                     </span>
                   </div>
@@ -1715,7 +1715,7 @@ exports[`Results Table Should match snapshot 1`] = `
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -1764,14 +1764,10 @@ exports[`Results Table Should match snapshot 1`] = `
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
-                              <span
-                                style="display: inline-flex; align-items: center; gap: 4px;"
-                              >
-                                0 %
-                              </span>
+                              -
                             </div>
                             <div
                               class="status cell"
@@ -1913,7 +1909,7 @@ exports[`Results Table Should match snapshot 1`] = `
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -1963,14 +1959,10 @@ exports[`Results Table Should match snapshot 1`] = `
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
-                              <span
-                                style="display: inline-flex; align-items: center; gap: 4px;"
-                              >
-                                0 %
-                              </span>
+                              -
                             </div>
                             <div
                               class="status cell"
@@ -2112,7 +2104,7 @@ exports[`Results Table Should match snapshot 1`] = `
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -2162,14 +2154,10 @@ exports[`Results Table Should match snapshot 1`] = `
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
-                              <span
-                                style="display: inline-flex; align-items: center; gap: 4px;"
-                              >
-                                0 %
-                              </span>
+                              -
                             </div>
                             <div
                               class="status cell"
@@ -2398,7 +2386,7 @@ exports[`Results Table Should match snapshot 1`] = `
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -2448,14 +2436,10 @@ exports[`Results Table Should match snapshot 1`] = `
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
-                              <span
-                                style="display: inline-flex; align-items: center; gap: 4px;"
-                              >
-                                0 %
-                              </span>
+                              -
                             </div>
                             <div
                               class="status cell"
@@ -4202,7 +4186,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                   </div>
                 </div>
                 <div
-                  class="fdtnfac f1l733lh"
+                  class="f1ozcnof f1l733lh"
                   data-testid="table-header"
                   role="row"
                 >
@@ -4269,16 +4253,16 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                     </span>
                   </div>
                   <div
-                    class="cell median-diff-header"
+                    class="cell mode-delta-header"
                     role="columnheader"
                   >
                     <span
-                      aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
                       <button
-                        aria-label="MD (%) (Click to sort by this column)"
+                        aria-label="Mode Δ (%) (Click to sort by this column)"
                         class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
                         tabindex="0"
                         type="button"
@@ -4294,10 +4278,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                             d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
                           />
                           <title>
-                            Not sorted by MD (%)
+                            Not sorted by Mode Δ (%)
                           </title>
                         </svg>
-                        MD (%)
+                        Mode Δ (%)
                       </button>
                     </span>
                   </div>
@@ -4598,7 +4582,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -4647,14 +4631,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
-                              <span
-                                style="display: inline-flex; align-items: center; gap: 4px;"
-                              >
-                                1.849 %
-                              </span>
+                              -
                             </div>
                             <div
                               class="status cell"
@@ -4809,7 +4789,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -4859,14 +4839,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
-                              <span
-                                style="display: inline-flex; align-items: center; gap: 4px;"
-                              >
-                                1.078 %
-                              </span>
+                              -
                             </div>
                             <div
                               class="status cell"
@@ -5021,7 +4997,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -5071,14 +5047,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
-                              <span
-                                style="display: inline-flex; align-items: center; gap: 4px;"
-                              >
-                                -2.401 %
-                              </span>
+                              -
                             </div>
                             <div
                               class="status cell"
@@ -5320,7 +5292,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                             role="row"
                           >
                             <div
@@ -5370,7 +5342,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                                
                             </div>
                             <div
-                              class="median-diff cell"
+                              class="mode-delta cell"
                               role="cell"
                             >
                               -
@@ -5835,32 +5807,32 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
 [
   "a11yr dhtml.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %",
+  "  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %",
+  "  - Linux 18.04, -, Regression, -, -, 45.00 %",
+  "  - Windows 10, -, , -, , 50.00 %",
   "  - Windows 10, -, , -, , 100.00 %",
-  "  - Windows 10, -2.401 %, , -, , 50.00 %",
   "  rev: tictactoe",
-  "  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %",
+  "  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %",
+  "  - Linux 18.04, -, Regression, 0.8, -, 44.00 %",
+  "  - Windows 10, -, , 0.8, , 49.00 %",
   "  - Windows 10, -, , 0.8, , 99.00 %",
-  "  - Windows 10, -2.401 %, , 0.8, , 49.00 %",
   "a11yr aria.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %",
+  "  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %",
+  "  - Linux 18.04, -, Regression, 1.2, -, 44.00 %",
+  "  - Windows 10, -, , 1.2, , 49.00 %",
   "  - Windows 10, -, , 1.2, , 99.00 %",
-  "  - Windows 10, -2.401 %, , 1.2, , 49.00 %",
   "  rev: tictactoe",
-  "  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %",
+  "  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %",
+  "  - Linux 18.04, -, Regression, 2, -, 43.00 %",
+  "  - Windows 10, -, , 2, , 48.00 %",
   "  - Windows 10, -, , 2, , 98.00 %",
-  "  - Windows 10, -2.401 %, , 2, , 48.00 %",
 ]
 `;
 
 exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion can sort params from the URL on mann-whitney-u test_version 9`] = `
 <button
-  aria-label="MD (%) (Currently sorted by this column. Click to change)"
+  aria-label="Mode Δ (%) (Currently sorted by this column. Click to change)"
   class="MuiButtonBase-root Mui-focusVisible MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
   tabindex="0"
   type="button"
@@ -5876,10 +5848,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
       d="M11 6.83 9.41 8.41 8 7l4-4 4 4-1.41 1.41L13 6.83V21h-2z"
     />
     <title>
-      Sorted by MD (%) in descending order
+      Sorted by Mode Δ (%) in descending order
     </title>
   </svg>
-  MD (%)
+  Mode Δ (%)
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -5907,32 +5879,32 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
 [
   "a11yr dhtml.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - Windows 10, -2.401 %, , -, , 50.00 %",
+  "  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %",
+  "  - Linux 18.04, -, Regression, -, -, 45.00 %",
+  "  - Windows 10, -, , -, , 50.00 %",
   "  - Windows 10, -, , -, , 100.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %",
-  "  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %",
   "  rev: tictactoe",
-  "  - Windows 10, -2.401 %, , 0.8, , 49.00 %",
+  "  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %",
+  "  - Linux 18.04, -, Regression, 0.8, -, 44.00 %",
+  "  - Windows 10, -, , 0.8, , 49.00 %",
   "  - Windows 10, -, , 0.8, , 99.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %",
-  "  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %",
   "a11yr aria.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - Windows 10, -2.401 %, , 1.2, , 49.00 %",
+  "  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %",
+  "  - Linux 18.04, -, Regression, 1.2, -, 44.00 %",
+  "  - Windows 10, -, , 1.2, , 49.00 %",
   "  - Windows 10, -, , 1.2, , 99.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %",
-  "  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %",
   "  rev: tictactoe",
-  "  - Windows 10, -2.401 %, , 2, , 48.00 %",
+  "  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %",
+  "  - Linux 18.04, -, Regression, 2, -, 43.00 %",
+  "  - Windows 10, -, , 2, , 48.00 %",
   "  - Windows 10, -, , 2, , 98.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %",
-  "  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %",
 ]
 `;
 
 exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion can sort params from the URL on mann-whitney-u test_version 11`] = `
 <button
-  aria-label="MD (%) (Currently sorted by this column. Click to change)"
+  aria-label="Mode Δ (%) (Currently sorted by this column. Click to change)"
   class="MuiButtonBase-root Mui-focusVisible MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
   tabindex="0"
   type="button"
@@ -5948,10 +5920,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
       d="M11 6.83 9.41 8.41 8 7l4-4 4 4-1.41 1.41L13 6.83V21h-2z"
     />
     <title>
-      Sorted by MD (%) in ascending order
+      Sorted by Mode Δ (%) in ascending order
     </title>
   </svg>
-  MD (%)
+  Mode Δ (%)
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -6135,7 +6107,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
       </span>
     </div>
     <div
-      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
       role="row"
     >
       <div
@@ -6185,14 +6157,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
          
       </div>
       <div
-        class="median-diff cell"
+        class="mode-delta cell"
         role="cell"
       >
-        <span
-          style="display: inline-flex; align-items: center; gap: 4px;"
-        >
-          1.078 %
-        </span>
+        -
       </div>
       <div
         class="status cell"
@@ -6386,7 +6354,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
       </span>
     </div>
     <div
-      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
       role="row"
     >
       <div
@@ -6436,14 +6404,10 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
          
       </div>
       <div
-        class="median-diff cell"
+        class="mode-delta cell"
         role="cell"
       >
-        <span
-          style="display: inline-flex; align-items: center; gap: 4px;"
-        >
-          1.078 %
-        </span>
+        -
       </div>
       <div
         class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index ae8cf9fbc..d595b8eea 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -1501,7 +1501,7 @@ exports[`Results View The table should match snapshot and other elements should
       </div>
     </div>
     <div
-      class="fdtnfac f1l733lh"
+      class="f1ozcnof f1l733lh"
       data-testid="table-header"
       role="row"
     >
@@ -1568,16 +1568,16 @@ exports[`Results View The table should match snapshot and other elements should
         </span>
       </div>
       <div
-        class="cell median-diff-header"
+        class="cell mode-delta-header"
         role="columnheader"
       >
         <span
-          aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
           <button
-            aria-label="MD (%) (Click to sort by this column)"
+            aria-label="Mode Δ (%) (Click to sort by this column)"
             class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
             tabindex="0"
             type="button"
@@ -1593,10 +1593,10 @@ exports[`Results View The table should match snapshot and other elements should
                 d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
               />
               <title>
-                Not sorted by MD (%)
+                Not sorted by Mode Δ (%)
               </title>
             </svg>
-            MD (%)
+            Mode Δ (%)
           </button>
         </span>
       </div>
@@ -1897,7 +1897,7 @@ exports[`Results View The table should match snapshot and other elements should
               class="revision-block fw0pvlu"
             >
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -1946,14 +1946,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -2095,7 +2091,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -2145,14 +2141,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -2294,7 +2286,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -2344,14 +2336,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -2493,7 +2481,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1woqe0l"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
                 role="row"
               >
                 <div
@@ -2543,14 +2531,10 @@ exports[`Results View The table should match snapshot and other elements should
                    
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index 18f8b99f1..f1f98e4b7 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -840,7 +840,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
               role="table"
             >
               <div
-                class="f1itjsvw f1l733lh"
+                class="f1epdax3 f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -900,16 +900,16 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   </span>
                 </div>
                 <div
-                  class="cell median-diff-header"
+                  class="cell mode-delta-header"
                   role="columnheader"
                 >
                   <span
-                    aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
                     <button
-                      aria-label="MD (%) (Click to sort by this column)"
+                      aria-label="Mode Δ (%) (Click to sort by this column)"
                       class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
                       tabindex="0"
                       type="button"
@@ -925,10 +925,10 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                           d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
                         />
                         <title>
-                          Not sorted by MD (%)
+                          Not sorted by Mode Δ (%)
                         </title>
                       </svg>
-                      MD (%)
+                      Mode Δ (%)
                     </button>
                   </span>
                 </div>
@@ -1112,7 +1112,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -1157,14 +1157,10 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   </span>
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -1274,7 +1270,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -1305,14 +1301,10 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -1422,7 +1414,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -1453,14 +1445,10 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -1570,7 +1558,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -1601,14 +1589,10 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -1718,7 +1702,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -1749,14 +1733,10 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -2751,7 +2731,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
               role="table"
             >
               <div
-                class="f1itjsvw f1l733lh"
+                class="f1epdax3 f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -2811,16 +2791,16 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   </span>
                 </div>
                 <div
-                  class="cell median-diff-header"
+                  class="cell mode-delta-header"
                   role="columnheader"
                 >
                   <span
-                    aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
                     <button
-                      aria-label="MD (%) (Click to sort by this column)"
+                      aria-label="Mode Δ (%) (Click to sort by this column)"
                       class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
                       tabindex="0"
                       type="button"
@@ -2836,10 +2816,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                           d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
                         />
                         <title>
-                          Not sorted by MD (%)
+                          Not sorted by Mode Δ (%)
                         </title>
                       </svg>
-                      MD (%)
+                      Mode Δ (%)
                     </button>
                   </span>
                 </div>
@@ -3023,7 +3003,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -3070,14 +3050,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   </span>
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.963 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -3187,7 +3163,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -3220,14 +3196,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    1.135 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -3363,7 +3335,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -3396,14 +3368,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.963 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -3526,7 +3494,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -3559,14 +3527,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    1.135 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -3689,7 +3653,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -3722,14 +3686,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.98 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -4353,7 +4313,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
               role="table"
             >
               <div
-                class="f1itjsvw f1l733lh"
+                class="f1epdax3 f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -4413,16 +4373,16 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   </span>
                 </div>
                 <div
-                  class="cell median-diff-header"
+                  class="cell mode-delta-header"
                   role="columnheader"
                 >
                   <span
-                    aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
                     <button
-                      aria-label="MD (%) (Click to sort by this column)"
+                      aria-label="Mode Δ (%) (Click to sort by this column)"
                       class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
                       tabindex="0"
                       type="button"
@@ -4438,10 +4398,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                           d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
                         />
                         <title>
-                          Not sorted by MD (%)
+                          Not sorted by Mode Δ (%)
                         </title>
                       </svg>
-                      MD (%)
+                      Mode Δ (%)
                     </button>
                   </span>
                 </div>
@@ -4625,7 +4585,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -4672,14 +4632,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   </span>
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.963 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -4789,7 +4745,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -4822,14 +4778,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    1.135 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -4965,7 +4917,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -4998,14 +4950,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.963 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -5128,7 +5076,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -5161,14 +5109,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    1.135 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -5291,7 +5235,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -5324,14 +5268,10 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.98 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -5955,7 +5895,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
               role="table"
             >
               <div
-                class="f1itjsvw f1l733lh"
+                class="f1epdax3 f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -6015,16 +5955,16 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   </span>
                 </div>
                 <div
-                  class="cell median-diff-header"
+                  class="cell mode-delta-header"
                   role="columnheader"
                 >
                   <span
-                    aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
                     <button
-                      aria-label="MD (%) (Click to sort by this column)"
+                      aria-label="Mode Δ (%) (Click to sort by this column)"
                       class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
                       tabindex="0"
                       type="button"
@@ -6040,10 +5980,10 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                           d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
                         />
                         <title>
-                          Not sorted by MD (%)
+                          Not sorted by Mode Δ (%)
                         </title>
                       </svg>
-                      MD (%)
+                      Mode Δ (%)
                     </button>
                   </span>
                 </div>
@@ -6227,7 +6167,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -6274,14 +6214,10 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   </span>
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.963 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -6391,7 +6327,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -6424,14 +6360,10 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    1.135 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -6567,7 +6499,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -6600,14 +6532,10 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.963 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -6730,7 +6658,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -6763,14 +6691,10 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    1.135 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -6893,7 +6817,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -6926,14 +6850,10 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0.98 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -7557,7 +7477,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
               role="table"
             >
               <div
-                class="f1itjsvw f1l733lh"
+                class="f1epdax3 f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -7617,16 +7537,16 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   </span>
                 </div>
                 <div
-                  class="cell median-diff-header"
+                  class="cell mode-delta-header"
                   role="columnheader"
                 >
                   <span
-                    aria-label="Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
                     <button
-                      aria-label="MD (%) (Click to sort by this column)"
+                      aria-label="Mode Δ (%) (Click to sort by this column)"
                       class="MuiButtonBase-root MuiButton-root MuiButton-contained MuiButton-containedTableHeaderButton MuiButton-sizeSmall MuiButton-containedSizeSmall MuiButton-colorTableHeaderButton MuiButton-disableElevation css-7upxw3-MuiButtonBase-root-MuiButton-root"
                       tabindex="0"
                       type="button"
@@ -7642,10 +7562,10 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                           d="M16 17.01V10h-2v7.01h-3L15 21l4-3.99zM9 3 5 6.99h3V14h2V6.99h3z"
                         />
                         <title>
-                          Not sorted by MD (%)
+                          Not sorted by Mode Δ (%)
                         </title>
                       </svg>
-                      MD (%)
+                      Mode Δ (%)
                     </button>
                   </span>
                 </div>
@@ -7829,7 +7749,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -7874,14 +7794,10 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   </span>
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -7991,7 +7907,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -8022,14 +7938,10 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -8139,7 +8051,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -8170,14 +8082,10 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -8287,7 +8195,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -8318,14 +8226,10 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
@@ -8435,7 +8339,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-185znds"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
                 role="row"
               >
                 <div
@@ -8466,14 +8370,10 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   ms
                 </div>
                 <div
-                  class="median-diff cell"
+                  class="mode-delta cell"
                   role="cell"
                 >
-                  <span
-                    style="display: inline-flex; align-items: center; gap: 4px;"
-                  >
-                    0 %
-                  </span>
+                  -
                 </div>
                 <div
                   class="status cell"
diff --git a/src/common/constants.ts b/src/common/constants.ts
index cdafa0247..615f668a1 100644
--- a/src/common/constants.ts
+++ b/src/common/constants.ts
@@ -337,5 +337,5 @@ export const tooltipConfidence =
   "Calculated using a Student's T-test comparison. Low is anything under a T value of 3, Medium is between 3 and 5, and High is anything higher than 5.";
 export const tooltipDelta =
   'The percentage difference between the Base and New values';
-export const tooltipMedianDiff =
-  'Median Diff %: The percentage change in median from Base to New: ((New − Base) / Base) × 100.';
+export const tooltipModeDelta =
+  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 742855fd4..4cafde5a0 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -1,7 +1,6 @@
 import KeyboardDoubleArrowUpIcon from '@mui/icons-material/KeyboardDoubleArrowUp';
 import ThumbDownIcon from '@mui/icons-material/ThumbDown';
 import ThumbUpIcon from '@mui/icons-material/ThumbUp';
-import WarningIcon from '@mui/icons-material/Warning';
 import Alert from '@mui/material/Alert';
 import Box from '@mui/material/Box';
 
@@ -17,6 +16,7 @@ import { TableConfig } from '../../types/types';
 import { bootstrapMedianDiffCI } from '../../utils/bootstrap-ci';
 import { adaptUnit, formatNumber } from '../../utils/format';
 import { capitalize } from '../../utils/helpers';
+import { computeLargestPeakShiftPct } from '../../utils/kdeAnalysis';
 import { getBrowserDisplay, getPlatformShortName } from '../../utils/platform';
 import {
   determineSign,
@@ -26,7 +26,7 @@ import { shapiroWilkTest } from '../../utils/shapiroWilk';
 import { defaultSortFunction } from '../../utils/sortFunctions';
 import {
   tooltipBaseMean,
-  tooltipMedianDiff,
+  tooltipModeDelta,
   tooltipNewMean,
   tooltipSignificance,
   tooltipStatusMannWhitney,
@@ -97,6 +97,30 @@ export function isDistributionNormal(result: MannWhitneyResultsItem): boolean {
   return checkDistributionNormality(result) !== 'neither';
 }
 
+/**
+ * Precompute the largest matched-pair peak shift % for every Mann-Whitney
+ * row and attach it to `result.modeDeltaPct`. Called from the data loaders
+ * so the Mode Δ column can sort without re-running KDE + mode matching
+ * per row per render (the whole pipeline — KDE, mode detection, modality
+ * matcher — is non-trivial and we don't want it in the sort hot path).
+ *
+ * `isSubtest` controls the bandwidth strategy used by KDE: subtest tables
+ * use ISJ, top-level tables use the wider SJ approximation. See
+ * `bandwidthFor` in kdeAnalysis.ts.
+ */
+export function precomputeLargestPeakShift(
+  results: MannWhitneyResultsItem[],
+  isSubtest: boolean,
+): void {
+  for (const result of results) {
+    result.modeDeltaPct = computeLargestPeakShiftPct(
+      result.base_runs ?? [],
+      result.new_runs ?? [],
+      isSubtest,
+    );
+  }
+}
+
 export const mannWhitneyStrategy = {
   getColumns(isSubtestTable: boolean): TableConfig {
     const platformConfig = isSubtestTable
@@ -133,25 +157,22 @@ export const mannWhitneyStrategy = {
       { key: 'comparisonSign', gridWidth: '0.25fr' },
       { name: 'New', key: 'new', gridWidth: '1fr', tooltip: tooltipNewMean },
       {
-        name: 'MD (%)',
-        key: 'median-diff',
-        gridWidth: '1fr',
+        name: 'Mode Δ (%)',
+        key: 'mode-delta',
+        gridWidth: '1.5fr',
         sortFunction(
           resultA: MannWhitneyResultsItem,
           resultB: MannWhitneyResultsItem,
         ) {
-          // Compute a normalized median diff percentage where positive
-          // means "improved" regardless of whether lower or higher is better.
-          const normalizedDiffPct = (r: MannWhitneyResultsItem) => {
-            const base = r.base_standard_stats?.median ?? 0;
-            const newVal = r.new_standard_stats?.median ?? 0;
-            const rawPct = base !== 0 ? ((newVal - base) / base) * 100 : 0;
-            return r.lower_is_better ? -rawPct : rawPct;
+          // Normalize sign so positive = "improved" regardless of metric
+          // direction; rows without a computed shift sort as 0.
+          const normalized = (r: MannWhitneyResultsItem) => {
+            const pct = r.modeDeltaPct ?? 0;
+            return r.lower_is_better ? -pct : pct;
           };
-
-          return normalizedDiffPct(resultB) - normalizedDiffPct(resultA);
+          return normalized(resultB) - normalized(resultA);
         },
-        tooltip: tooltipMedianDiff,
+        tooltip: tooltipModeDelta,
       },
       {
         name: 'Status',
@@ -295,34 +316,12 @@ export const mannWhitneyStrategy = {
             <span className={FontSize.xSmall}>({newApp})</span>
           )}
         </div>
-        <div className='median-diff cell' role='cell'>
+        <div className='mode-delta cell' role='cell'>
           {(() => {
-            const mwResult = result as MannWhitneyResultsItem;
-            const normality = checkDistributionNormality(mwResult);
-            if (normality === 'neither') return '-';
-            const baseMedian = mwResult.base_standard_stats?.median ?? 0;
-            const newMedian = mwResult.new_standard_stats?.median ?? 0;
-            const pct =
-              baseMedian !== 0
-                ? ((newMedian - baseMedian) / baseMedian) * 100
-                : 0;
-            return (
-              <span
-                style={{
-                  display: 'inline-flex',
-                  alignItems: 'center',
-                  gap: '4px',
-                }}
-              >
-                {`${formatNumber(pct)} %`}
-                {normality === 'one' && (
-                  <WarningIcon
-                    titleAccess="Distribution shapes aren't normal."
-                    sx={{ fontSize: '0.9rem', opacity: 0.5, ml: '4px' }}
-                  />
-                )}
-              </span>
-            );
+            const pct = (result as MannWhitneyResultsItem).modeDeltaPct;
+            return pct === null || pct === undefined
+              ? '-'
+              : `${pct.toFixed(2)} %`;
           })()}
         </div>
         <div className='status cell' role='cell'>
@@ -480,40 +479,16 @@ export const mannWhitneyStrategy = {
       direction_of_change,
       mann_whitney_test,
       cles,
-      base_standard_stats,
-      new_standard_stats,
+      modeDeltaPct,
     } = result as MannWhitneyResultsItem;
     const clesValue = cles?.cles ? `${(cles.cles * 100).toFixed(2)} %` : '-';
-    const baseMedian = base_standard_stats?.median ?? 0;
-    const newMedian = new_standard_stats?.median ?? 0;
-    const medianDiffPct =
-      baseMedian !== 0 ? ((newMedian - baseMedian) / baseMedian) * 100 : 0;
-    const normality = checkDistributionNormality(
-      result as MannWhitneyResultsItem,
-    );
 
     return (
       <>
-        <div className='median-diff cell' role='cell'>
-          {normality === 'neither' ? (
-            '-'
-          ) : (
-            <span
-              style={{
-                display: 'inline-flex',
-                alignItems: 'center',
-                gap: '4px',
-              }}
-            >
-              {`${formatNumber(medianDiffPct)} %`}
-              {normality === 'one' && (
-                <WarningIcon
-                  titleAccess="Distribution shapes aren't normal."
-                  sx={{ fontSize: '0.9rem', opacity: 0.5, ml: '4px' }}
-                />
-              )}
-            </span>
-          )}
+        <div className='mode-delta cell' role='cell'>
+          {modeDeltaPct === null || modeDeltaPct === undefined
+            ? '-'
+            : `${modeDeltaPct.toFixed(2)} %`}
         </div>
         <div className='status cell' role='cell'>
           <Box
diff --git a/src/components/CompareResults/loader.ts b/src/components/CompareResults/loader.ts
index 06916b6e6..0739681cb 100644
--- a/src/components/CompareResults/loader.ts
+++ b/src/components/CompareResults/loader.ts
@@ -4,6 +4,7 @@ import {
   compareView,
   MANN_WHITNEY_U,
 } from '../../common/constants';
+import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
 import {
   fetchCompareResults,
   fetchFakeCompareResults,
@@ -12,6 +13,7 @@ import {
 import {
   Changeset,
   CombinedResultsItemType,
+  MannWhitneyResultsItem,
   Repository,
 } from '../../types/state';
 import { FakeCommitHash, Framework, TestVersion } from '../../types/types';
@@ -197,6 +199,14 @@ export async function loader({ request }: { request: Request }) {
   const useFakeData = url.searchParams.has('fakedata');
   if (useFakeData) {
     const results = await fetchAllFakeCompareResults();
+    // Fake results are Mann-Whitney shaped; precompute the Mode Δ per row
+    // so the column behaves like it would on real backend data.
+    for (const oneRevsResults of results) {
+      precomputeLargestPeakShift(
+        oneRevsResults as unknown as MannWhitneyResultsItem[],
+        false,
+      );
+    }
     // They're all based on the same rev
     const baseRev = results[0][0].base_rev;
     // And the same repository
@@ -292,6 +302,19 @@ export async function getComparisonInformation(
     replicates,
     testVersion,
     silvermanKDEEnabled,
+  }).then((results) => {
+    // Precompute the Mode Δ (largest matched-pair peak shift %) per row so
+    // the column can sort without re-running KDE + mode matching per
+    // sortFunction call. Top-level (non-subtest) table → isSubtest=false.
+    if (testVersion === MANN_WHITNEY_U) {
+      for (const oneRevsResults of results) {
+        precomputeLargestPeakShift(
+          oneRevsResults as unknown as MannWhitneyResultsItem[],
+          false,
+        );
+      }
+    }
+    return results;
   });
 
   // TODO what happens if there's no result?
diff --git a/src/components/CompareResults/overTimeLoader.ts b/src/components/CompareResults/overTimeLoader.ts
index 206d04d04..d6bd30c67 100644
--- a/src/components/CompareResults/overTimeLoader.ts
+++ b/src/components/CompareResults/overTimeLoader.ts
@@ -5,6 +5,7 @@ import {
   compareOverTimeView,
   MANN_WHITNEY_U,
 } from '../../common/constants';
+import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
 import {
   fetchCompareOverTimeResults,
   memoizedFetchRevisionForRepository,
@@ -12,6 +13,7 @@ import {
 import {
   Changeset,
   CombinedResultsItemType,
+  MannWhitneyResultsItem,
   Repository,
 } from '../../types/state';
 import { Framework, TestVersion, TimeRange } from '../../types/types';
@@ -228,6 +230,16 @@ export async function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
+  }).then((results) => {
+    if (testVersion === MANN_WHITNEY_U) {
+      for (const oneRevsResults of results) {
+        precomputeLargestPeakShift(
+          oneRevsResults as unknown as MannWhitneyResultsItem[],
+          false,
+        );
+      }
+    }
+    return results;
   });
 
   const newRevsInfoPromises = newRevs.map((newRev, i) =>
diff --git a/src/components/CompareResults/subtestsLoader.ts b/src/components/CompareResults/subtestsLoader.ts
index 2e381b7ea..a39384cc0 100644
--- a/src/components/CompareResults/subtestsLoader.ts
+++ b/src/components/CompareResults/subtestsLoader.ts
@@ -1,6 +1,7 @@
 import { repoMap, frameworks, MANN_WHITNEY_U } from '../../common/constants';
+import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
 import { fetchSubtestsCompareResults } from '../../logic/treeherder';
-import { Repository } from '../../types/state';
+import { MannWhitneyResultsItem, Repository } from '../../types/state';
 import { Framework, TestVersion } from '../../types/types';
 
 // This function checks and sanitizes the input values, then returns values that
@@ -186,6 +187,16 @@ export function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
+  }).then((subtestResults) => {
+    // Subtests use ISJ bandwidth (narrower, data-driven) for Mode Δ since
+    // they typically have more samples than top-level aggregated rows.
+    if (testVersion === MANN_WHITNEY_U) {
+      precomputeLargestPeakShift(
+        subtestResults as unknown as MannWhitneyResultsItem[],
+        true,
+      );
+    }
+    return subtestResults;
   });
 
   return {
diff --git a/src/components/CompareResults/subtestsOverTimeLoader.tsx b/src/components/CompareResults/subtestsOverTimeLoader.tsx
index 906926b21..4da8373a7 100644
--- a/src/components/CompareResults/subtestsOverTimeLoader.tsx
+++ b/src/components/CompareResults/subtestsOverTimeLoader.tsx
@@ -4,8 +4,9 @@ import {
   timeRanges,
   MANN_WHITNEY_U,
 } from '../../common/constants';
+import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
 import { fetchSubtestsCompareOverTimeResults } from '../../logic/treeherder';
-import { Repository } from '../../types/state';
+import { MannWhitneyResultsItem, Repository } from '../../types/state';
 import { Framework, TestVersion, TimeRange } from '../../types/types';
 
 // This function checks and sanitizes the input values, then returns values that
@@ -212,6 +213,14 @@ export function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
+  }).then((subtestResults) => {
+    if (testVersion === MANN_WHITNEY_U) {
+      precomputeLargestPeakShift(
+        subtestResults as unknown as MannWhitneyResultsItem[],
+        true,
+      );
+    }
+    return subtestResults;
   });
 
   return {
diff --git a/src/types/state.ts b/src/types/state.ts
index 2091e09ef..13a3ff395 100644
--- a/src/types/state.ts
+++ b/src/types/state.ts
@@ -242,6 +242,12 @@ export type MannWhitneyResultsItem = {
   is_meaningful: boolean | null;
   more_runs_are_needed: boolean | null;
   warning_c_delta?: string | null;
+  // Largest matched-pair peak shift (signed, as % of base peak location)
+  // from KDE mode detection on base_runs/new_runs. Precomputed by the
+  // Mann-Whitney loader so the Mode Δ column can sort without re-running
+  // KDE + mode matching per row per render. `null` when the pipeline
+  // can't yield a value — see computeLargestPeakShiftPct.
+  modeDeltaPct?: number | null;
   /*
   Each test has a signature and each signature may or may not have a parent_signature.
   If a signature has a parent_signature then we are looking at a subtest. For regular tests this field will be null.
diff --git a/src/utils/kdeAnalysis.ts b/src/utils/kdeAnalysis.ts
index 2a3ff0795..0950d1954 100644
--- a/src/utils/kdeAnalysis.ts
+++ b/src/utils/kdeAnalysis.ts
@@ -9,6 +9,7 @@ import {
   fftkde,
   fitModesFromKde,
   improvedSheatherJones,
+  matchModes,
   silvermansRule,
 } from './kde.js';
 
@@ -137,3 +138,62 @@ export function computeModeInfo(
     letters: assignLetters(peakLocs),
   };
 }
+
+/**
+ * Compute the largest matched-pair peak shift between base and new
+ * distributions, expressed as a percentage of the base peak location.
+ *
+ * Pipeline: same as `KdeModesPanel` — shared bandwidth (max of per-side
+ * `bandwidthFor`), `safeKde` both sides, `computeModeInfo` to get peaks +
+ * area fractions, `matchModes` to align base/new peaks. Then for every
+ * matched pair, computes `(newLoc - baseLoc) / baseLoc * 100` and returns
+ * the one with the largest absolute value (signed — positive means the
+ * new peak shifted higher).
+ *
+ * Returns `null` when:
+ *   - either side has < 2 samples
+ *   - either KDE fails (e.g. degenerate inputs)
+ *   - mode detection finds no peaks on either side
+ *   - no matched pairs (e.g. only unmatched modes — disappeared/appeared paths)
+ *   - the only matched base peaks are at exactly zero (can't divide)
+ *
+ * @param valleyThreshold Passed to `fitModesFromKde`. Defaults to 0.5 to
+ *   match `RevisionRowExpandable`'s slider default; the precompute path
+ *   has no slider to read from.
+ */
+export function computeLargestPeakShiftPct(
+  baseValues: number[],
+  newValues: number[],
+  isSubtest: boolean,
+  valleyThreshold: number = 0.5,
+): number | null {
+  if (baseValues.length < 2 || newValues.length < 2) return null;
+  const baseBw = bandwidthFor(baseValues, isSubtest) ?? 0;
+  const newBw = bandwidthFor(newValues, isSubtest) ?? 0;
+  const rawSharedBw = Math.max(baseBw, newBw);
+  const sharedBw = rawSharedBw > 0 ? rawSharedBw : undefined;
+  const bKde = safeKde(baseValues, sharedBw);
+  const nKde = safeKde(newValues, sharedBw);
+  if (!bKde || !nKde) return null;
+  const bModes = computeModeInfo(bKde.x, bKde.y, valleyThreshold);
+  const nModes = computeModeInfo(nKde.x, nKde.y, valleyThreshold);
+  if (!bModes.peakLocs.length || !nModes.peakLocs.length) return null;
+  const { pairs } = matchModes(
+    bModes.peakLocs,
+    bModes.fracs,
+    nModes.peakLocs,
+    nModes.fracs,
+  );
+  if (!pairs.length) return null;
+  let bestPct: number | null = null;
+  for (const [bi, ni] of pairs) {
+    const baseLoc = bModes.peakLocs[bi];
+    const newLoc = nModes.peakLocs[ni];
+    if (baseLoc === 0) continue;
+    const pct = ((newLoc - baseLoc) / baseLoc) * 100;
+    if (bestPct === null || Math.abs(pct) > Math.abs(bestPct)) {
+      bestPct = pct;
+    }
+  }
+  return bestPct;
+}

From d052f2968db7dd8c99e15317476cead1e4846dee Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 15:27:34 -0700
Subject: [PATCH 2/9] TableHeader: show info icon next to columns with
 explanatory tooltips

Mode change: dash to NM instead - No modes
---
 .../CompareResults/ResultsTable.test.tsx      | 298 +++++------
 .../SubtestsResultsView.test.tsx              | 100 ++--
 .../OverTimeResultsView.test.tsx.snap         |  75 ++-
 .../__snapshots__/ResultsTable.test.tsx.snap  | 310 +++++++++--
 .../__snapshots__/ResultsView.test.tsx.snap   |  75 ++-
 .../SubtestsResultsView.test.tsx.snap         | 483 +++++++++++++++---
 src/common/constants.ts                       |   2 +-
 src/common/testVersions/mannWhitney.tsx       |  19 +-
 src/components/CompareResults/TableHeader.tsx |  21 +
 src/types/types.ts                            |   3 +
 10 files changed, 1043 insertions(+), 343 deletions(-)

diff --git a/src/__tests__/CompareResults/ResultsTable.test.tsx b/src/__tests__/CompareResults/ResultsTable.test.tsx
index 57e9f4930..e0808db90 100644
--- a/src/__tests__/CompareResults/ResultsTable.test.tsx
+++ b/src/__tests__/CompareResults/ResultsTable.test.tsx
@@ -722,9 +722,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
       '  rev: devilrabbit',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(screen.getByRole('rowgroup')).toMatchSnapshot();
   });
@@ -748,12 +748,12 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await screen.findByText('a11yr');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
 
     expect(summarizeTableFiltersFromUrl()).toEqual({});
@@ -762,9 +762,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Windows/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'linux', 'android', 'ios'],
@@ -775,12 +775,12 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Windows/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
@@ -788,8 +788,8 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Linux/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios'],
@@ -798,9 +798,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Linux/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios', 'linux'],
@@ -809,22 +809,22 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', 'Select all values');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
     await clickMenuItem(user, 'Platform', /macOS/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['windows', 'linux', 'android', 'ios'],
@@ -833,9 +833,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Android/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['windows', 'linux', 'ios'],
@@ -844,7 +844,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Select only.*Android/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, -, Improvement, 0.1, -, 25.00 %',
+      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['android'],
@@ -883,10 +883,10 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await screen.findByText('a11yr');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
@@ -894,8 +894,8 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /No changes/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['improvement', 'regression'],
@@ -904,7 +904,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Improvement/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -914,9 +914,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['none', 'improvement'],
@@ -925,17 +925,17 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
     await clickMenuItem(user, 'Status', /Select only.*Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -944,7 +944,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Select only.*Improvement/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['improvement'],
@@ -961,7 +961,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
 
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
     ]);
     const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
     expect(await summarizeTableFiltersFromCheckboxes(user)).toEqual({
@@ -997,26 +997,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
-      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - Windows 10, -, , 1.2, , 49.00 %',
+      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
+      '  - Windows 10, NM, , 1.2, , 99.00 %',
+      '  - Windows 10, NM, , 1.2, , 49.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
-      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
-      '  - Windows 10, -, , 2, , 48.00 %',
+      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
+      '  - Windows 10, NM, , 2, , 98.00 %',
+      '  - Windows 10, NM, , 2, , 48.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
-      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - Windows 10, -, , 0.8, , 49.00 %',
+      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
+      '  - Windows 10, NM, , 0.8, , 99.00 %',
+      '  - Windows 10, NM, , 0.8, , 49.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(deltaButton).toMatchSnapshot();
@@ -1028,26 +1028,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
-      '  - Windows 10, -, , 2, , 48.00 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
+      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
+      '  - Windows 10, NM, , 2, , 48.00 %',
+      '  - Windows 10, NM, , 2, , 98.00 %',
       '  rev: spam',
-      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, -, , 1.2, , 49.00 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
+      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, NM, , 1.2, , 49.00 %',
+      '  - Windows 10, NM, , 1.2, , 99.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, -, , 0.8, , 49.00 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, NM, , 0.8, , 49.00 %',
+      '  - Windows 10, NM, , 0.8, , 99.00 %',
       '  rev: spam',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
     ]);
     // It should have the "ascending" SVG.
     expect(deltaButton).toMatchSnapshot();
@@ -1062,26 +1062,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
-      '  - Windows 10, -, , 2, , 48.00 %',
+      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
+      '  - Windows 10, NM, , 2, , 98.00 %',
+      '  - Windows 10, NM, , 2, , 48.00 %',
       '  rev: spam',
-      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - Windows 10, -, , 1.2, , 49.00 %',
+      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, NM, , 1.2, , 99.00 %',
+      '  - Windows 10, NM, , 1.2, , 49.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - Windows 10, -, , 0.8, , 49.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, NM, , 0.8, , 99.00 %',
+      '  - Windows 10, NM, , 0.8, , 49.00 %',
       '  rev: spam',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(significanceButton).toMatchSnapshot();
@@ -1093,26 +1093,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -, , -, , 50.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -, , 0.8, , 49.00 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, NM, , 0.8, , 49.00 %',
+      '  - Windows 10, NM, , 0.8, , 99.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -, , 1.2, , 49.00 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, NM, , 1.2, , 49.00 %',
+      '  - Windows 10, NM, , 1.2, , 99.00 %',
+      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -, , 2, , 48.00 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
-      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
+      '  - Windows 10, NM, , 2, , 48.00 %',
+      '  - Windows 10, NM, , 2, , 98.00 %',
+      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(significanceButton).toMatchSnapshot();
@@ -1127,26 +1127,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - Windows 10, -, , -, , 50.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
-      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, -, , 0.8, , 49.00 %',
+      '  - Windows 10, NM, , 0.8, , 99.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, NM, , 0.8, , 49.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, -, , 1.2, , 49.00 %',
+      '  - Windows 10, NM, , 1.2, , 99.00 %',
+      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, NM, , 1.2, , 49.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -, , 2, , 98.00 %',
-      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
-      '  - Windows 10, -, , 2, , 48.00 %',
+      '  - Windows 10, NM, , 2, , 98.00 %',
+      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
+      '  - Windows 10, NM, , 2, , 48.00 %',
     ]);
 
     expect(effectSizeButton).toMatchSnapshot();
@@ -1158,26 +1158,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -, , -, , 50.00 %',
-      '  - Linux 18.04, -, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, NM, , -, , 100.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -, , 0.8, , 49.00 %',
-      '  - Linux 18.04, -, Regression, 0.8, -, 44.00 %',
-      '  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
+      '  - Windows 10, NM, , 0.8, , 49.00 %',
+      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
+      '  - Windows 10, NM, , 0.8, , 99.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, -, , 1.2, , 49.00 %',
-      '  - Linux 18.04, -, Regression, 1.2, -, 44.00 %',
-      '  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
+      '  - Windows 10, NM, , 1.2, , 49.00 %',
+      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
+      '  - Windows 10, NM, , 1.2, , 99.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, -, , 2, , 48.00 %',
-      '  - Linux 18.04, -, Regression, 2, -, 43.00 %',
-      '  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
+      '  - Windows 10, NM, , 2, , 48.00 %',
+      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
+      '  - Windows 10, NM, , 2, , 98.00 %',
     ]);
     expect(effectSizeButton).toMatchSnapshot();
     // It should be persisted in the URL
diff --git a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
index aaf94410d..06ab1010f 100644
--- a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
@@ -527,11 +527,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting();
       // Initial view (alphabetical ordered, even if "sort by subtests" isn't specified
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: -, -0.04, -, 15.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'improvement.html: -, -0.05, , 50.00%',
-        'regression.html: -, 0.12, , 25.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
       ]);
 
       // Sort by Delta
@@ -542,11 +542,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort descending
       await user.click(deltaButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: -, 0.12, , 25.00%',
-        'improvement.html: -, -0.05, , 50.00%',
-        'browser.html: -, -0.04, -, 15.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
       ]);
 
       // It should have the "descending" SVG.
@@ -557,11 +557,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort ascending
       await user.click(deltaButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'tablemutation.html: -, 0.01, -, 45.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'browser.html: -, -0.04, -, 15.00%',
-        'improvement.html: -, -0.05, , 50.00%',
-        'regression.html: -, 0.12, , 25.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'regression.html: NM, 0.12, , 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -574,11 +574,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       });
       await user.click(significanceButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: -, -0.04, -, 15.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'regression.html: -, 0.12, , 25.00%',
-        'improvement.html: -, -0.05, , 50.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
       ]);
       // It should have the "no sort" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -590,11 +590,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort by Significance ascending
       await user.click(significanceButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'improvement.html: -, -0.05, , 50.00%',
-        'regression.html: -, 0.12, , 25.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
-        'browser.html: -, -0.04, -, 15.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'significance|asc');
 
@@ -604,11 +604,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       });
       await user.click(effectButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: -, -0.04, -, 15.00%',
-        'regression.html: -, 0.12, , 25.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
-        'improvement.html: -, -0.05, , 50.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
       ]);
 
       // It should have the "descending" SVG.
@@ -619,11 +619,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort by Effect Size ascending
       await user.click(effectButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'improvement.html: -, -0.05, , 50.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'regression.html: -, 0.12, , 25.00%',
-        'browser.html: -, -0.04, -, 15.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'effects|asc');
     });
@@ -632,11 +632,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting({ extraParameters: 'sort=delta|asc' });
       await screen.findByText('dhtml.html');
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'tablemutation.html: -, 0.01, -, 45.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'browser.html: -, -0.04, -, 15.00%',
-        'improvement.html: -, -0.05, , 50.00%',
-        'regression.html: -, 0.12, , 25.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'regression.html: NM, 0.12, , 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -646,11 +646,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting({ extraParameters: 'sort=delta' });
       await screen.findByText('dhtml.html');
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: -, 0.12, , 25.00%',
-        'improvement.html: -, -0.05, , 50.00%',
-        'browser.html: -, -0.04, -, 15.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -659,11 +659,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
     it('initializes the sort from the URL at load time for a descending sort', async () => {
       await setupForSorting({ extraParameters: 'sort=delta|desc' });
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: -, 0.12, , 25.00%',
-        'improvement.html: -, -0.05, , 50.00%',
-        'browser.html: -, -0.04, -, 15.00%',
-        'dhtml.html: -, 0.02, , 60.00%',
-        'tablemutation.html: -, 0.01, -, 45.00%',
+        'regression.html: NM, 0.12, , 25.00%',
+        'improvement.html: NM, -0.05, , 50.00%',
+        'browser.html: NM, -0.04, -, 15.00%',
+        'dhtml.html: NM, 0.02, , 60.00%',
+        'tablemutation.html: NM, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index 8d866e9f2..e06bf3c70 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -346,7 +346,7 @@ exports[`Results View The table should match snapshot and other elements should
       </div>
     </div>
     <div
-      class="f1ozcnof f1l733lh"
+      class="f1a6m55i f1l733lh"
       data-testid="table-header"
       role="row"
     >
@@ -417,7 +417,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
@@ -442,6 +442,17 @@ exports[`Results View The table should match snapshot and other elements should
               </title>
             </svg>
             Mode Δ (%)
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
           </button>
         </span>
       </div>
@@ -458,6 +469,17 @@ exports[`Results View The table should match snapshot and other elements should
           type="button"
         >
           Status
+          <svg
+            aria-hidden="true"
+            class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+            data-testid="InfoOutlinedIcon"
+            focusable="false"
+            viewBox="0 0 24 24"
+          >
+            <path
+              d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+            />
+          </svg>
           <div
             aria-label="3 items selected"
             class="MuiBox-root css-18uhbjh"
@@ -508,6 +530,17 @@ exports[`Results View The table should match snapshot and other elements should
               </title>
             </svg>
             CD
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
           </button>
         </span>
       </div>
@@ -540,6 +573,17 @@ exports[`Results View The table should match snapshot and other elements should
               </title>
             </svg>
             CLES (%)
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
           </button>
         </span>
       </div>
@@ -581,6 +625,17 @@ exports[`Results View The table should match snapshot and other elements should
             type="button"
           >
             Sig
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
             <div
               aria-label="2 items selected"
               class="MuiBox-root css-18uhbjh"
@@ -742,7 +797,7 @@ exports[`Results View The table should match snapshot and other elements should
               class="revision-block fw0pvlu"
             >
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -794,7 +849,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -936,7 +991,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -989,7 +1044,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -1131,7 +1186,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -1184,7 +1239,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -1326,7 +1381,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -1379,7 +1434,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index 286a50900..a103d7925 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1319,7 +1319,7 @@ exports[`Results Table Should match snapshot 1`] = `
                   </div>
                 </div>
                 <div
-                  class="f1ozcnof f1l733lh"
+                  class="f1a6m55i f1l733lh"
                   data-testid="table-header"
                   role="row"
                 >
@@ -1390,7 +1390,7 @@ exports[`Results Table Should match snapshot 1`] = `
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
@@ -1415,6 +1415,17 @@ exports[`Results Table Should match snapshot 1`] = `
                           </title>
                         </svg>
                         Mode Δ (%)
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                       </button>
                     </span>
                   </div>
@@ -1431,6 +1442,17 @@ exports[`Results Table Should match snapshot 1`] = `
                       type="button"
                     >
                       Status
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                       <div
                         aria-label="3 items selected"
                         class="MuiBox-root css-18uhbjh"
@@ -1481,6 +1503,17 @@ exports[`Results Table Should match snapshot 1`] = `
                           </title>
                         </svg>
                         CD
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                       </button>
                     </span>
                   </div>
@@ -1513,6 +1546,17 @@ exports[`Results Table Should match snapshot 1`] = `
                           </title>
                         </svg>
                         CLES (%)
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                       </button>
                     </span>
                   </div>
@@ -1554,6 +1598,17 @@ exports[`Results Table Should match snapshot 1`] = `
                         type="button"
                       >
                         Sig
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                         <div
                           aria-label="2 items selected"
                           class="MuiBox-root css-18uhbjh"
@@ -1715,7 +1770,7 @@ exports[`Results Table Should match snapshot 1`] = `
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -1767,7 +1822,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -1909,7 +1964,7 @@ exports[`Results Table Should match snapshot 1`] = `
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -1962,7 +2017,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -2104,7 +2159,7 @@ exports[`Results Table Should match snapshot 1`] = `
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -2157,7 +2212,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -2386,7 +2441,7 @@ exports[`Results Table Should match snapshot 1`] = `
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -2439,7 +2494,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -4186,7 +4241,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                   </div>
                 </div>
                 <div
-                  class="f1ozcnof f1l733lh"
+                  class="f1a6m55i f1l733lh"
                   data-testid="table-header"
                   role="row"
                 >
@@ -4257,7 +4312,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
@@ -4282,6 +4337,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                           </title>
                         </svg>
                         Mode Δ (%)
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                       </button>
                     </span>
                   </div>
@@ -4298,6 +4364,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                       type="button"
                     >
                       Status
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                       <div
                         aria-label="3 items selected"
                         class="MuiBox-root css-18uhbjh"
@@ -4348,6 +4425,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                           </title>
                         </svg>
                         CD
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                       </button>
                     </span>
                   </div>
@@ -4380,6 +4468,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                           </title>
                         </svg>
                         CLES (%)
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                       </button>
                     </span>
                   </div>
@@ -4421,6 +4520,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                         type="button"
                       >
                         Sig
+                        <svg
+                          aria-hidden="true"
+                          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                          data-testid="InfoOutlinedIcon"
+                          focusable="false"
+                          viewBox="0 0 24 24"
+                        >
+                          <path
+                            d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                          />
+                        </svg>
                         <div
                           aria-label="2 items selected"
                           class="MuiBox-root css-18uhbjh"
@@ -4582,7 +4692,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -4634,7 +4744,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -4789,7 +4899,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -4842,7 +4952,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -4997,7 +5107,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                             </div>
                           </div>
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -5050,7 +5160,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -5292,7 +5402,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                           class="revision-block fw0pvlu"
                         >
                           <div
-                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                            class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                             role="row"
                           >
                             <div
@@ -5345,7 +5455,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              -
+                              NM
                             </div>
                             <div
                               class="status cell"
@@ -5536,6 +5646,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
 </button>
 `;
 
@@ -5561,6 +5682,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
 </button>
 `;
 
@@ -5586,6 +5718,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -5727,6 +5870,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
     </title>
   </svg>
   CLES (%)
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -5772,6 +5926,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
     </title>
   </svg>
   CLES (%)
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -5807,26 +5972,26 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
 [
   "a11yr dhtml.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %",
-  "  - Linux 18.04, -, Regression, -, -, 45.00 %",
-  "  - Windows 10, -, , -, , 50.00 %",
-  "  - Windows 10, -, , -, , 100.00 %",
+  "  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %",
+  "  - Linux 18.04, NM, Regression, -, -, 45.00 %",
+  "  - Windows 10, NM, , -, , 50.00 %",
+  "  - Windows 10, NM, , -, , 100.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %",
-  "  - Linux 18.04, -, Regression, 0.8, -, 44.00 %",
-  "  - Windows 10, -, , 0.8, , 49.00 %",
-  "  - Windows 10, -, , 0.8, , 99.00 %",
+  "  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %",
+  "  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %",
+  "  - Windows 10, NM, , 0.8, , 49.00 %",
+  "  - Windows 10, NM, , 0.8, , 99.00 %",
   "a11yr aria.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %",
-  "  - Linux 18.04, -, Regression, 1.2, -, 44.00 %",
-  "  - Windows 10, -, , 1.2, , 49.00 %",
-  "  - Windows 10, -, , 1.2, , 99.00 %",
+  "  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %",
+  "  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %",
+  "  - Windows 10, NM, , 1.2, , 49.00 %",
+  "  - Windows 10, NM, , 1.2, , 99.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %",
-  "  - Linux 18.04, -, Regression, 2, -, 43.00 %",
-  "  - Windows 10, -, , 2, , 48.00 %",
-  "  - Windows 10, -, , 2, , 98.00 %",
+  "  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %",
+  "  - Linux 18.04, NM, Regression, 2, -, 43.00 %",
+  "  - Windows 10, NM, , 2, , 48.00 %",
+  "  - Windows 10, NM, , 2, , 98.00 %",
 ]
 `;
 
@@ -5852,6 +6017,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
     </title>
   </svg>
   Mode Δ (%)
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -5879,26 +6055,26 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
 [
   "a11yr dhtml.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, -, Improvement, 0.1, -, 25.00 %",
-  "  - Linux 18.04, -, Regression, -, -, 45.00 %",
-  "  - Windows 10, -, , -, , 50.00 %",
-  "  - Windows 10, -, , -, , 100.00 %",
+  "  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %",
+  "  - Linux 18.04, NM, Regression, -, -, 45.00 %",
+  "  - Windows 10, NM, , -, , 50.00 %",
+  "  - Windows 10, NM, , -, , 100.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, -, Improvement, 0.9, -, 24.00 %",
-  "  - Linux 18.04, -, Regression, 0.8, -, 44.00 %",
-  "  - Windows 10, -, , 0.8, , 49.00 %",
-  "  - Windows 10, -, , 0.8, , 99.00 %",
+  "  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %",
+  "  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %",
+  "  - Windows 10, NM, , 0.8, , 49.00 %",
+  "  - Windows 10, NM, , 0.8, , 99.00 %",
   "a11yr aria.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, -, Improvement, 1.3, -, 24.00 %",
-  "  - Linux 18.04, -, Regression, 1.2, -, 44.00 %",
-  "  - Windows 10, -, , 1.2, , 49.00 %",
-  "  - Windows 10, -, , 1.2, , 99.00 %",
+  "  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %",
+  "  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %",
+  "  - Windows 10, NM, , 1.2, , 49.00 %",
+  "  - Windows 10, NM, , 1.2, , 99.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, -, Improvement, 2.1, -, 23.00 %",
-  "  - Linux 18.04, -, Regression, 2, -, 43.00 %",
-  "  - Windows 10, -, , 2, , 48.00 %",
-  "  - Windows 10, -, , 2, , 98.00 %",
+  "  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %",
+  "  - Linux 18.04, NM, Regression, 2, -, 43.00 %",
+  "  - Windows 10, NM, , 2, , 48.00 %",
+  "  - Windows 10, NM, , 2, , 98.00 %",
 ]
 `;
 
@@ -5924,6 +6100,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
     </title>
   </svg>
   Mode Δ (%)
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -5966,6 +6153,17 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
   type="button"
 >
   Sig
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <div
     aria-label="2 items selected"
     class="MuiBox-root css-18uhbjh"
@@ -6107,7 +6305,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
       </span>
     </div>
     <div
-      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
       role="row"
     >
       <div
@@ -6160,7 +6358,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="mode-delta cell"
         role="cell"
       >
-        -
+        NM
       </div>
       <div
         class="status cell"
@@ -6354,7 +6552,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
       </span>
     </div>
     <div
-      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+      class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
       role="row"
     >
       <div
@@ -6407,7 +6605,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="mode-delta cell"
         role="cell"
       >
-        -
+        NM
       </div>
       <div
         class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index d595b8eea..8a3779e3f 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -1501,7 +1501,7 @@ exports[`Results View The table should match snapshot and other elements should
       </div>
     </div>
     <div
-      class="f1ozcnof f1l733lh"
+      class="f1a6m55i f1l733lh"
       data-testid="table-header"
       role="row"
     >
@@ -1572,7 +1572,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
@@ -1597,6 +1597,17 @@ exports[`Results View The table should match snapshot and other elements should
               </title>
             </svg>
             Mode Δ (%)
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
           </button>
         </span>
       </div>
@@ -1613,6 +1624,17 @@ exports[`Results View The table should match snapshot and other elements should
           type="button"
         >
           Status
+          <svg
+            aria-hidden="true"
+            class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+            data-testid="InfoOutlinedIcon"
+            focusable="false"
+            viewBox="0 0 24 24"
+          >
+            <path
+              d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+            />
+          </svg>
           <div
             aria-label="3 items selected"
             class="MuiBox-root css-18uhbjh"
@@ -1663,6 +1685,17 @@ exports[`Results View The table should match snapshot and other elements should
               </title>
             </svg>
             CD
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
           </button>
         </span>
       </div>
@@ -1695,6 +1728,17 @@ exports[`Results View The table should match snapshot and other elements should
               </title>
             </svg>
             CLES (%)
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
           </button>
         </span>
       </div>
@@ -1736,6 +1780,17 @@ exports[`Results View The table should match snapshot and other elements should
             type="button"
           >
             Sig
+            <svg
+              aria-hidden="true"
+              class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+              data-testid="InfoOutlinedIcon"
+              focusable="false"
+              viewBox="0 0 24 24"
+            >
+              <path
+                d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+              />
+            </svg>
             <div
               aria-label="2 items selected"
               class="MuiBox-root css-18uhbjh"
@@ -1897,7 +1952,7 @@ exports[`Results View The table should match snapshot and other elements should
               class="revision-block fw0pvlu"
             >
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -1949,7 +2004,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -2091,7 +2146,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -2144,7 +2199,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -2286,7 +2341,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -2339,7 +2394,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -2481,7 +2536,7 @@ exports[`Results View The table should match snapshot and other elements should
                 </div>
               </div>
               <div
-                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-lkxut"
+                class="revisionRow f1wmgkbg f1dlt78d MuiBox-root css-1iua0ib"
                 role="row"
               >
                 <div
@@ -2534,7 +2589,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index f1f98e4b7..81d68caa8 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -22,6 +22,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
 </button>
 `;
 
@@ -47,6 +58,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -92,6 +114,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -145,6 +178,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -242,6 +286,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CLES (%)
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
   <span
     class="MuiTouchRipple-root css-r3djoj-MuiTouchRipple-root"
   >
@@ -287,6 +342,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
 </button>
 `;
 
@@ -312,6 +378,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
 </button>
 `;
 
@@ -337,6 +414,17 @@ exports[`SubtestsResultsView Component Tests for mann-whitney-u testVersion tabl
     </title>
   </svg>
   CD
+  <svg
+    aria-hidden="true"
+    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+    data-testid="InfoOutlinedIcon"
+    focusable="false"
+    viewBox="0 0 24 24"
+  >
+    <path
+      d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+    />
+  </svg>
 </button>
 `;
 
@@ -840,7 +928,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
               role="table"
             >
               <div
-                class="f1epdax3 f1l733lh"
+                class="f18geslq f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -904,7 +992,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -929,6 +1017,17 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                         </title>
                       </svg>
                       Mode Δ (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -945,6 +1044,17 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                     type="button"
                   >
                     Status
+                    <svg
+                      aria-hidden="true"
+                      class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                      data-testid="InfoOutlinedIcon"
+                      focusable="false"
+                      viewBox="0 0 24 24"
+                    >
+                      <path
+                        d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                      />
+                    </svg>
                     <div
                       aria-label="3 items selected"
                       class="MuiBox-root css-18uhbjh"
@@ -995,6 +1105,17 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                         </title>
                       </svg>
                       CD
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -1027,6 +1148,17 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                         </title>
                       </svg>
                       CLES (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -1068,6 +1200,17 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                       type="button"
                     >
                       Sig
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                       <div
                         aria-label="2 items selected"
                         class="MuiBox-root css-18uhbjh"
@@ -1112,7 +1255,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -1160,7 +1303,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -1270,7 +1413,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -1304,7 +1447,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -1414,7 +1557,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -1448,7 +1591,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -1558,7 +1701,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -1592,7 +1735,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -1702,7 +1845,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -1736,7 +1879,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -2731,7 +2874,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
               role="table"
             >
               <div
-                class="f1epdax3 f1l733lh"
+                class="f18geslq f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -2795,7 +2938,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -2820,6 +2963,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                         </title>
                       </svg>
                       Mode Δ (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -2836,6 +2990,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                     type="button"
                   >
                     Status
+                    <svg
+                      aria-hidden="true"
+                      class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                      data-testid="InfoOutlinedIcon"
+                      focusable="false"
+                      viewBox="0 0 24 24"
+                    >
+                      <path
+                        d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                      />
+                    </svg>
                     <div
                       aria-label="3 items selected"
                       class="MuiBox-root css-18uhbjh"
@@ -2886,6 +3051,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                         </title>
                       </svg>
                       CD
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -2918,6 +3094,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                         </title>
                       </svg>
                       CLES (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -2959,6 +3146,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                       type="button"
                     >
                       Sig
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                       <div
                         aria-label="2 items selected"
                         class="MuiBox-root css-18uhbjh"
@@ -3003,7 +3201,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -3053,7 +3251,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -3163,7 +3361,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -3199,7 +3397,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -3335,7 +3533,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -3371,7 +3569,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -3494,7 +3692,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -3530,7 +3728,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -3653,7 +3851,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -3689,7 +3887,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -4313,7 +4511,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
               role="table"
             >
               <div
-                class="f1epdax3 f1l733lh"
+                class="f18geslq f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -4377,7 +4575,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -4402,6 +4600,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                         </title>
                       </svg>
                       Mode Δ (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -4418,6 +4627,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                     type="button"
                   >
                     Status
+                    <svg
+                      aria-hidden="true"
+                      class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                      data-testid="InfoOutlinedIcon"
+                      focusable="false"
+                      viewBox="0 0 24 24"
+                    >
+                      <path
+                        d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                      />
+                    </svg>
                     <div
                       aria-label="3 items selected"
                       class="MuiBox-root css-18uhbjh"
@@ -4468,6 +4688,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                         </title>
                       </svg>
                       CD
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -4500,6 +4731,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                         </title>
                       </svg>
                       CLES (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -4541,6 +4783,17 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                       type="button"
                     >
                       Sig
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                       <div
                         aria-label="2 items selected"
                         class="MuiBox-root css-18uhbjh"
@@ -4585,7 +4838,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -4635,7 +4888,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -4745,7 +4998,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -4781,7 +5034,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -4917,7 +5170,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -4953,7 +5206,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -5076,7 +5329,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -5112,7 +5365,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -5235,7 +5488,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -5271,7 +5524,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -5895,7 +6148,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
               role="table"
             >
               <div
-                class="f1epdax3 f1l733lh"
+                class="f18geslq f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -5959,7 +6212,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -5984,6 +6237,17 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                         </title>
                       </svg>
                       Mode Δ (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -6000,6 +6264,17 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                     type="button"
                   >
                     Status
+                    <svg
+                      aria-hidden="true"
+                      class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                      data-testid="InfoOutlinedIcon"
+                      focusable="false"
+                      viewBox="0 0 24 24"
+                    >
+                      <path
+                        d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                      />
+                    </svg>
                     <div
                       aria-label="3 items selected"
                       class="MuiBox-root css-18uhbjh"
@@ -6050,6 +6325,17 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                         </title>
                       </svg>
                       CD
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -6082,6 +6368,17 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                         </title>
                       </svg>
                       CLES (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -6123,6 +6420,17 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                       type="button"
                     >
                       Sig
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                       <div
                         aria-label="2 items selected"
                         class="MuiBox-root css-18uhbjh"
@@ -6167,7 +6475,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -6217,7 +6525,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -6327,7 +6635,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -6363,7 +6671,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -6499,7 +6807,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -6535,7 +6843,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -6658,7 +6966,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -6694,7 +7002,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -6817,7 +7125,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -6853,7 +7161,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -7477,7 +7785,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
               role="table"
             >
               <div
-                class="f1epdax3 f1l733lh"
+                class="f18geslq f1l733lh"
                 data-testid="table-header"
                 role="row"
               >
@@ -7541,7 +7849,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -7566,6 +7874,17 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                         </title>
                       </svg>
                       Mode Δ (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -7582,6 +7901,17 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                     type="button"
                   >
                     Status
+                    <svg
+                      aria-hidden="true"
+                      class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                      data-testid="InfoOutlinedIcon"
+                      focusable="false"
+                      viewBox="0 0 24 24"
+                    >
+                      <path
+                        d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                      />
+                    </svg>
                     <div
                       aria-label="3 items selected"
                       class="MuiBox-root css-18uhbjh"
@@ -7632,6 +7962,17 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                         </title>
                       </svg>
                       CD
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -7664,6 +8005,17 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                         </title>
                       </svg>
                       CLES (%)
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                     </button>
                   </span>
                 </div>
@@ -7705,6 +8057,17 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                       type="button"
                     >
                       Sig
+                      <svg
+                        aria-hidden="true"
+                        class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1ltkupd-MuiSvgIcon-root"
+                        data-testid="InfoOutlinedIcon"
+                        focusable="false"
+                        viewBox="0 0 24 24"
+                      >
+                        <path
+                          d="M11 7h2v2h-2zm0 4h2v6h-2zm1-9C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2m0 18c-4.41 0-8-3.59-8-8s3.59-8 8-8 8 3.59 8 8-3.59 8-8 8"
+                        />
+                      </svg>
                       <div
                         aria-label="2 items selected"
                         class="MuiBox-root css-18uhbjh"
@@ -7749,7 +8112,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 />
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -7797,7 +8160,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -7907,7 +8270,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -7941,7 +8304,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -8051,7 +8414,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -8085,7 +8448,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -8195,7 +8558,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -8229,7 +8592,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
@@ -8339,7 +8702,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                 </div>
               </div>
               <div
-                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-1p0zhuz"
+                class="revisionRow f146qxgq f1dlt78d MuiBox-root css-16hvrzr"
                 role="row"
               >
                 <div
@@ -8373,7 +8736,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  -
+                  NM
                 </div>
                 <div
                   class="status cell"
diff --git a/src/common/constants.ts b/src/common/constants.ts
index 615f668a1..1134792da 100644
--- a/src/common/constants.ts
+++ b/src/common/constants.ts
@@ -338,4 +338,4 @@ export const tooltipConfidence =
 export const tooltipDelta =
   'The percentage difference between the Base and New values';
 export const tooltipModeDelta =
-  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. A dash (-) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
+  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 4cafde5a0..a66e1b1be 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -159,7 +159,7 @@ export const mannWhitneyStrategy = {
       {
         name: 'Mode Δ (%)',
         key: 'mode-delta',
-        gridWidth: '1.5fr',
+        gridWidth: '1.75fr',
         sortFunction(
           resultA: MannWhitneyResultsItem,
           resultB: MannWhitneyResultsItem,
@@ -173,12 +173,14 @@ export const mannWhitneyStrategy = {
           return normalized(resultB) - normalized(resultA);
         },
         tooltip: tooltipModeDelta,
+        tooltipIcon: true,
       },
       {
         name: 'Status',
         filter: true,
         key: 'status',
-        gridWidth: '1.5fr',
+        gridWidth: '1.75fr',
+        tooltipIcon: true,
         possibleValues: [
           { label: 'No changes', key: 'none' },
           { label: 'Improvement', key: 'improvement' },
@@ -202,7 +204,7 @@ export const mannWhitneyStrategy = {
       {
         name: 'CD',
         key: 'delta',
-        gridWidth: '1fr',
+        gridWidth: '1.25fr',
         sortFunction(
           resultA: MannWhitneyResultsItem,
           resultB: MannWhitneyResultsItem,
@@ -212,11 +214,13 @@ export const mannWhitneyStrategy = {
           );
         },
         tooltip: tooltipCliffsDelta,
+        tooltipIcon: true,
       },
       {
         name: 'CLES (%)',
         key: 'effects',
-        gridWidth: '1.25fr',
+        gridWidth: '1.5fr',
+        tooltipIcon: true,
         sortFunction(
           resultA: MannWhitneyResultsItem,
           resultB: MannWhitneyResultsItem,
@@ -232,8 +236,9 @@ export const mannWhitneyStrategy = {
         name: 'Sig',
         key: 'significance',
         filter: true,
-        gridWidth: '1.25fr',
+        gridWidth: '1.5fr',
         tooltip: tooltipSignificance,
+        tooltipIcon: true,
         possibleValues: [
           {
             label: 'Significant',
@@ -320,7 +325,7 @@ export const mannWhitneyStrategy = {
           {(() => {
             const pct = (result as MannWhitneyResultsItem).modeDeltaPct;
             return pct === null || pct === undefined
-              ? '-'
+              ? 'NM'
               : `${pct.toFixed(2)} %`;
           })()}
         </div>
@@ -487,7 +492,7 @@ export const mannWhitneyStrategy = {
       <>
         <div className='mode-delta cell' role='cell'>
           {modeDeltaPct === null || modeDeltaPct === undefined
-            ? '-'
+            ? 'NM'
             : `${modeDeltaPct.toFixed(2)} %`}
         </div>
         <div className='status cell' role='cell'>
diff --git a/src/components/CompareResults/TableHeader.tsx b/src/components/CompareResults/TableHeader.tsx
index 6e6c55490..6a81ba233 100644
--- a/src/components/CompareResults/TableHeader.tsx
+++ b/src/components/CompareResults/TableHeader.tsx
@@ -1,5 +1,6 @@
 import { ReactNode } from 'react';
 
+import InfoOutlinedIcon from '@mui/icons-material/InfoOutlined';
 import KeyboardArrowDownIcon from '@mui/icons-material/KeyboardArrowDown';
 import StraightIcon from '@mui/icons-material/Straight';
 import SwapVert from '@mui/icons-material/SwapVert';
@@ -68,6 +69,17 @@ function SortDirectionIcon({
   }
 }
 
+// Render a small "info" icon. Used in column headers when a hover-tooltip
+// is attached, so the tooltip is discoverable instead of hidden until hover.
+function InfoIconHint() {
+  return (
+    <InfoOutlinedIcon
+      fontSize='small'
+      sx={{ fontSize: '0.95rem', opacity: 0.6, marginInlineStart: 0.5 }}
+    />
+  );
+}
+
 type FilterableColumnHeaderProps = {
   name: string;
   columnId: string;
@@ -78,6 +90,7 @@ type FilterableColumnHeaderProps = {
   onToggleFilter: (checkedValues: Set<string>) => unknown;
   onClearFilter: () => unknown;
   tooltip?: ReactNode;
+  showInfoIcon?: boolean;
 };
 
 function FilterableColumnHeader({
@@ -87,6 +100,7 @@ function FilterableColumnHeader({
   checkedValues,
   onToggleFilter,
   onClearFilter,
+  showInfoIcon,
   tooltip,
 }: FilterableColumnHeaderProps) {
   const popupState = usePopupState({ variant: 'popover', popupId: columnId });
@@ -127,6 +141,7 @@ function FilterableColumnHeader({
           sx={{ paddingInline: 1.5, fontSize: '16px' }}
         >
           {name}
+          {showInfoIcon && <InfoIconHint />}
           <Box
             sx={{
               paddingInlineStart: 0.5,
@@ -211,6 +226,7 @@ type SortableColumnHeaderProps = {
   displayLabel: boolean;
   sortDirection: 'asc' | 'desc' | null;
   onToggle: (sortDirection: SortableColumnHeaderProps['sortDirection']) => void;
+  showInfoIcon?: boolean;
 };
 
 function SortableColumnHeader({
@@ -218,6 +234,7 @@ function SortableColumnHeader({
   displayLabel,
   sortDirection,
   onToggle,
+  showInfoIcon,
 }: SortableColumnHeaderProps) {
   const buttonAriaLabel = sortDirection
     ? `${name} (Currently sorted by this column. Click to change)`
@@ -263,6 +280,7 @@ function SortableColumnHeader({
         sx={inlineIconStyle}
       />
       {displayLabel ? name : null}
+      {displayLabel && showInfoIcon ? <InfoIconHint /> : null}
     </Button>
   );
 }
@@ -365,6 +383,7 @@ function TableHeader({
               onToggleFilter(header.key, checkedValues)
             }
             tooltip={header.tooltip}
+            showInfoIcon={header.tooltipIcon}
           />
         </ButtonGroup>
       );
@@ -377,6 +396,7 @@ function TableHeader({
           onToggle={(newSortDirection) =>
             onToggleSort(header.key, newSortDirection)
           }
+          showInfoIcon={header.tooltipIcon}
         />
       );
     } else if ('filter' in header) {
@@ -391,6 +411,7 @@ function TableHeader({
             onToggleFilter(header.key, checkedValues)
           }
           tooltip={header.tooltip}
+          showInfoIcon={header.tooltipIcon}
         />
       );
     }
diff --git a/src/types/types.ts b/src/types/types.ts
index 962134a0e..a43556aba 100644
--- a/src/types/types.ts
+++ b/src/types/types.ts
@@ -17,6 +17,9 @@ export interface BasicColumn {
   // Used in the grid CSS property to configure the width of the column.
   gridWidth: string;
   tooltip?: React.ReactNode;
+  // When true, render a small info icon next to the column title so users
+  // know a hover-tooltip is available. Opt-in per column.
+  tooltipIcon?: boolean;
 }
 
 // This interface is used for a column that can be filtered.

From 1f8491d3dda2f107c6020a1184c5d953de47b10d Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 15:55:24 -0700
Subject: [PATCH 3/9] mannWhitney: unify modality analysis as single source of
 truth

---
 .../__snapshots__/ResultsView.test.tsx.snap   | 20 +++--
 src/common/testVersions/mannWhitney.tsx       | 21 ++++--
 .../MannWhitneyCompareMetrics.tsx             |  8 +-
 src/components/CompareResults/loader.ts       |  6 +-
 .../CompareResults/overTimeLoader.ts          |  4 +-
 .../CompareResults/subtestsLoader.ts          |  4 +-
 .../CompareResults/subtestsOverTimeLoader.tsx |  4 +-
 src/types/state.ts                            | 13 ++--
 src/utils/kdeAnalysis.ts                      | 73 +++++++++++++------
 9 files changed, 99 insertions(+), 54 deletions(-)

diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index 8a3779e3f..398e1446e 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -355,7 +355,7 @@ exports[`Results View Should display Base, New and Common graphs with replicates
         style="display: flex;"
       >
         <div
-          class="MuiBox-root css-104qrv3"
+          class="mann-whitney-compare-metrics MuiBox-root css-104qrv3"
         >
           <table
             style="display: grid; grid: 1fr; gap: 2px; flex-direction: column;"
@@ -530,8 +530,12 @@ exports[`Results View Should display Base, New and Common graphs with replicates
                 <td>
                   Estimated Modes
                 </td>
-                <td />
-                <td />
+                <td>
+                  0
+                </td>
+                <td>
+                  0
+                </td>
                 <td>
                   No modes or data for Base and New, possible oversmoothing, KDE evaluation failed
                 </td>
@@ -900,7 +904,7 @@ exports[`Results View Should display Base, New and Common graphs with tooltips 1
         style="display: flex;"
       >
         <div
-          class="MuiBox-root css-104qrv3"
+          class="mann-whitney-compare-metrics MuiBox-root css-104qrv3"
         >
           <table
             style="display: grid; grid: 1fr; gap: 2px; flex-direction: column;"
@@ -1075,8 +1079,12 @@ exports[`Results View Should display Base, New and Common graphs with tooltips 1
                 <td>
                   Estimated Modes
                 </td>
-                <td />
-                <td />
+                <td>
+                  0
+                </td>
+                <td>
+                  0
+                </td>
                 <td>
                   No modes or data for Base and New, possible oversmoothing, KDE evaluation failed
                 </td>
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index a66e1b1be..a2fe44295 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -16,7 +16,7 @@ import { TableConfig } from '../../types/types';
 import { bootstrapMedianDiffCI } from '../../utils/bootstrap-ci';
 import { adaptUnit, formatNumber } from '../../utils/format';
 import { capitalize } from '../../utils/helpers';
-import { computeLargestPeakShiftPct } from '../../utils/kdeAnalysis';
+import { computeModalityAnalysis } from '../../utils/kdeAnalysis';
 import { getBrowserDisplay, getPlatformShortName } from '../../utils/platform';
 import {
   determineSign,
@@ -98,26 +98,31 @@ export function isDistributionNormal(result: MannWhitneyResultsItem): boolean {
 }
 
 /**
- * Precompute the largest matched-pair peak shift % for every Mann-Whitney
- * row and attach it to `result.modeDeltaPct`. Called from the data loaders
- * so the Mode Δ column can sort without re-running KDE + mode matching
- * per row per render (the whole pipeline — KDE, mode detection, modality
- * matcher — is non-trivial and we don't want it in the sort hot path).
+ * Precompute the client-side modality analysis for every Mann-Whitney row
+ * and attach the relevant fields (`modeDeltaPct`, `baseModeCount`,
+ * `newModeCount`) to the result. Called from the data loaders so every UI
+ * that talks about modes — the Mode Δ column sort/cell, the Distribution
+ * Interpretation row in MannWhitneyCompareMetrics, KdeModesPanel — reads
+ * from the same numbers instead of mixing client-side ISJ output with the
+ * backend's wider Silverman counts (which used to disagree).
  *
  * `isSubtest` controls the bandwidth strategy used by KDE: subtest tables
  * use ISJ, top-level tables use the wider SJ approximation. See
  * `bandwidthFor` in kdeAnalysis.ts.
  */
-export function precomputeLargestPeakShift(
+export function precomputeModalityAnalysis(
   results: MannWhitneyResultsItem[],
   isSubtest: boolean,
 ): void {
   for (const result of results) {
-    result.modeDeltaPct = computeLargestPeakShiftPct(
+    const analysis = computeModalityAnalysis(
       result.base_runs ?? [],
       result.new_runs ?? [],
       isSubtest,
     );
+    result.modeDeltaPct = analysis.largestPeakShiftPct;
+    result.baseModeCount = analysis.baseModes.peakLocs.length;
+    result.newModeCount = analysis.newModes.peakLocs.length;
   }
 }
 
diff --git a/src/components/CompareResults/MannWhitneyCompareMetrics.tsx b/src/components/CompareResults/MannWhitneyCompareMetrics.tsx
index 1cead497e..b30d91a8e 100644
--- a/src/components/CompareResults/MannWhitneyCompareMetrics.tsx
+++ b/src/components/CompareResults/MannWhitneyCompareMetrics.tsx
@@ -52,11 +52,15 @@ export const MannWhitneyCompareMetrics = ({
     result.shapiro_wilk_test_base?.interpretation ?? 'N/A';
   const newShapiroWilkInterpretation =
     result.shapiro_wilk_test_new?.interpretation ?? 'N/A';
-  const baseMode = result?.silverman_kde?.base_mode_count ?? null;
-  const newMode = result?.silverman_kde?.new_mode_count ?? null;
+  // Mode counts come from the precomputed client-side modality pipeline
+  // (see precomputeModalityAnalysis), not from the backend's wider-bandwidth
+  // Silverman KDE — otherwise this row could contradict the Mode Δ column.
+  const baseMode = result?.baseModeCount ?? null;
+  const newMode = result?.newModeCount ?? null;
 
   return (
     <Box
+      className='mann-whitney-compare-metrics'
       sx={{
         backgroundColor: 'manWhitneyComps.compareMetricsBg',
         marginBottom: 2,
diff --git a/src/components/CompareResults/loader.ts b/src/components/CompareResults/loader.ts
index 0739681cb..679ed20cb 100644
--- a/src/components/CompareResults/loader.ts
+++ b/src/components/CompareResults/loader.ts
@@ -4,7 +4,7 @@ import {
   compareView,
   MANN_WHITNEY_U,
 } from '../../common/constants';
-import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
+import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import {
   fetchCompareResults,
   fetchFakeCompareResults,
@@ -202,7 +202,7 @@ export async function loader({ request }: { request: Request }) {
     // Fake results are Mann-Whitney shaped; precompute the Mode Δ per row
     // so the column behaves like it would on real backend data.
     for (const oneRevsResults of results) {
-      precomputeLargestPeakShift(
+      precomputeModalityAnalysis(
         oneRevsResults as unknown as MannWhitneyResultsItem[],
         false,
       );
@@ -308,7 +308,7 @@ export async function getComparisonInformation(
     // sortFunction call. Top-level (non-subtest) table → isSubtest=false.
     if (testVersion === MANN_WHITNEY_U) {
       for (const oneRevsResults of results) {
-        precomputeLargestPeakShift(
+        precomputeModalityAnalysis(
           oneRevsResults as unknown as MannWhitneyResultsItem[],
           false,
         );
diff --git a/src/components/CompareResults/overTimeLoader.ts b/src/components/CompareResults/overTimeLoader.ts
index d6bd30c67..3f123913d 100644
--- a/src/components/CompareResults/overTimeLoader.ts
+++ b/src/components/CompareResults/overTimeLoader.ts
@@ -5,7 +5,7 @@ import {
   compareOverTimeView,
   MANN_WHITNEY_U,
 } from '../../common/constants';
-import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
+import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import {
   fetchCompareOverTimeResults,
   memoizedFetchRevisionForRepository,
@@ -233,7 +233,7 @@ export async function loader({ request }: { request: Request }) {
   }).then((results) => {
     if (testVersion === MANN_WHITNEY_U) {
       for (const oneRevsResults of results) {
-        precomputeLargestPeakShift(
+        precomputeModalityAnalysis(
           oneRevsResults as unknown as MannWhitneyResultsItem[],
           false,
         );
diff --git a/src/components/CompareResults/subtestsLoader.ts b/src/components/CompareResults/subtestsLoader.ts
index a39384cc0..d94c7e785 100644
--- a/src/components/CompareResults/subtestsLoader.ts
+++ b/src/components/CompareResults/subtestsLoader.ts
@@ -1,5 +1,5 @@
 import { repoMap, frameworks, MANN_WHITNEY_U } from '../../common/constants';
-import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
+import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import { fetchSubtestsCompareResults } from '../../logic/treeherder';
 import { MannWhitneyResultsItem, Repository } from '../../types/state';
 import { Framework, TestVersion } from '../../types/types';
@@ -191,7 +191,7 @@ export function loader({ request }: { request: Request }) {
     // Subtests use ISJ bandwidth (narrower, data-driven) for Mode Δ since
     // they typically have more samples than top-level aggregated rows.
     if (testVersion === MANN_WHITNEY_U) {
-      precomputeLargestPeakShift(
+      precomputeModalityAnalysis(
         subtestResults as unknown as MannWhitneyResultsItem[],
         true,
       );
diff --git a/src/components/CompareResults/subtestsOverTimeLoader.tsx b/src/components/CompareResults/subtestsOverTimeLoader.tsx
index 4da8373a7..e7d5bb577 100644
--- a/src/components/CompareResults/subtestsOverTimeLoader.tsx
+++ b/src/components/CompareResults/subtestsOverTimeLoader.tsx
@@ -4,7 +4,7 @@ import {
   timeRanges,
   MANN_WHITNEY_U,
 } from '../../common/constants';
-import { precomputeLargestPeakShift } from '../../common/testVersions/mannWhitney';
+import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import { fetchSubtestsCompareOverTimeResults } from '../../logic/treeherder';
 import { MannWhitneyResultsItem, Repository } from '../../types/state';
 import { Framework, TestVersion, TimeRange } from '../../types/types';
@@ -215,7 +215,7 @@ export function loader({ request }: { request: Request }) {
     silvermanKDEEnabled,
   }).then((subtestResults) => {
     if (testVersion === MANN_WHITNEY_U) {
-      precomputeLargestPeakShift(
+      precomputeModalityAnalysis(
         subtestResults as unknown as MannWhitneyResultsItem[],
         true,
       );
diff --git a/src/types/state.ts b/src/types/state.ts
index 13a3ff395..da54f1226 100644
--- a/src/types/state.ts
+++ b/src/types/state.ts
@@ -242,12 +242,15 @@ export type MannWhitneyResultsItem = {
   is_meaningful: boolean | null;
   more_runs_are_needed: boolean | null;
   warning_c_delta?: string | null;
-  // Largest matched-pair peak shift (signed, as % of base peak location)
-  // from KDE mode detection on base_runs/new_runs. Precomputed by the
-  // Mann-Whitney loader so the Mode Δ column can sort without re-running
-  // KDE + mode matching per row per render. `null` when the pipeline
-  // can't yield a value — see computeLargestPeakShiftPct.
+  // Client-side modality analysis precomputed by the Mann-Whitney loader.
+  // Single source of truth for any UI that needs to talk about modes (the
+  // Mode Δ column, the Distribution Interpretation row, KdeModesPanel) so
+  // those views can't drift onto different mode-detection logic. `null`
+  // means we never ran the pipeline (legacy/stale data). See
+  // computeModalityAnalysis in kdeAnalysis.ts.
   modeDeltaPct?: number | null;
+  baseModeCount?: number | null;
+  newModeCount?: number | null;
   /*
   Each test has a signature and each signature may or may not have a parent_signature.
   If a signature has a parent_signature then we are looking at a subtest. For regular tests this field will be null.
diff --git a/src/utils/kdeAnalysis.ts b/src/utils/kdeAnalysis.ts
index 0950d1954..7ba2d4e2e 100644
--- a/src/utils/kdeAnalysis.ts
+++ b/src/utils/kdeAnalysis.ts
@@ -140,60 +140,85 @@ export function computeModeInfo(
 }
 
 /**
- * Compute the largest matched-pair peak shift between base and new
- * distributions, expressed as a percentage of the base peak location.
+ * Combined output of the client-side modality pipeline. Used as the single
+ * source of truth for any UI that needs to talk about modes (counts in the
+ * Distribution Interpretation row, the Mode Δ column, KdeModesPanel, etc.)
+ * so the page never contradicts itself.
+ */
+export type ModalityAnalysis = {
+  baseModes: ModeInfo;
+  newModes: ModeInfo;
+  // Largest matched-pair peak shift as % of base peak location; null when
+  // KDE/mode/matching produced nothing usable. See computeModalityAnalysis.
+  largestPeakShiftPct: number | null;
+};
+
+export const EMPTY_MODALITY_ANALYSIS: ModalityAnalysis = {
+  baseModes: EMPTY_MODE_INFO,
+  newModes: EMPTY_MODE_INFO,
+  largestPeakShiftPct: null,
+};
+
+/**
+ * Run the full client-side modality pipeline for a base/new pair.
  *
- * Pipeline: same as `KdeModesPanel` — shared bandwidth (max of per-side
+ * Pipeline (same as `KdeModesPanel`): shared bandwidth (max of per-side
  * `bandwidthFor`), `safeKde` both sides, `computeModeInfo` to get peaks +
- * area fractions, `matchModes` to align base/new peaks. Then for every
- * matched pair, computes `(newLoc - baseLoc) / baseLoc * 100` and returns
- * the one with the largest absolute value (signed — positive means the
- * new peak shifted higher).
+ * area fractions, `matchModes` to align base/new peaks. Then derives the
+ * largest matched-pair peak shift, as a signed percentage of the base peak
+ * location (positive = new peak shifted higher).
  *
- * Returns `null` when:
+ * `largestPeakShiftPct` is `null` when:
  *   - either side has < 2 samples
  *   - either KDE fails (e.g. degenerate inputs)
  *   - mode detection finds no peaks on either side
- *   - no matched pairs (e.g. only unmatched modes — disappeared/appeared paths)
+ *   - no matched pairs (e.g. only unmatched modes — paths appeared/disappeared)
  *   - the only matched base peaks are at exactly zero (can't divide)
  *
+ * Mode counts (`baseModes.peakLocs.length` / `newModes.peakLocs.length`)
+ * are 0 in the same conditions that drive `largestPeakShiftPct` to null
+ * (except the divide-by-zero case, which still yields counts).
+ *
  * @param valleyThreshold Passed to `fitModesFromKde`. Defaults to 0.5 to
  *   match `RevisionRowExpandable`'s slider default; the precompute path
  *   has no slider to read from.
  */
-export function computeLargestPeakShiftPct(
+export function computeModalityAnalysis(
   baseValues: number[],
   newValues: number[],
   isSubtest: boolean,
   valleyThreshold: number = 0.5,
-): number | null {
-  if (baseValues.length < 2 || newValues.length < 2) return null;
+): ModalityAnalysis {
+  if (baseValues.length < 2 || newValues.length < 2) {
+    return EMPTY_MODALITY_ANALYSIS;
+  }
   const baseBw = bandwidthFor(baseValues, isSubtest) ?? 0;
   const newBw = bandwidthFor(newValues, isSubtest) ?? 0;
   const rawSharedBw = Math.max(baseBw, newBw);
   const sharedBw = rawSharedBw > 0 ? rawSharedBw : undefined;
   const bKde = safeKde(baseValues, sharedBw);
   const nKde = safeKde(newValues, sharedBw);
-  if (!bKde || !nKde) return null;
-  const bModes = computeModeInfo(bKde.x, bKde.y, valleyThreshold);
-  const nModes = computeModeInfo(nKde.x, nKde.y, valleyThreshold);
-  if (!bModes.peakLocs.length || !nModes.peakLocs.length) return null;
+  if (!bKde || !nKde) return EMPTY_MODALITY_ANALYSIS;
+  const baseModes = computeModeInfo(bKde.x, bKde.y, valleyThreshold);
+  const newModes = computeModeInfo(nKde.x, nKde.y, valleyThreshold);
+  if (!baseModes.peakLocs.length || !newModes.peakLocs.length) {
+    return { baseModes, newModes, largestPeakShiftPct: null };
+  }
   const { pairs } = matchModes(
-    bModes.peakLocs,
-    bModes.fracs,
-    nModes.peakLocs,
-    nModes.fracs,
+    baseModes.peakLocs,
+    baseModes.fracs,
+    newModes.peakLocs,
+    newModes.fracs,
   );
-  if (!pairs.length) return null;
   let bestPct: number | null = null;
   for (const [bi, ni] of pairs) {
-    const baseLoc = bModes.peakLocs[bi];
-    const newLoc = nModes.peakLocs[ni];
+    const baseLoc = baseModes.peakLocs[bi];
+    const newLoc = newModes.peakLocs[ni];
     if (baseLoc === 0) continue;
     const pct = ((newLoc - baseLoc) / baseLoc) * 100;
     if (bestPct === null || Math.abs(pct) > Math.abs(bestPct)) {
       bestPct = pct;
     }
   }
-  return bestPct;
+  return { baseModes, newModes, largestPeakShiftPct: bestPct };
 }

From 4efb2e24d4c0a95153d40320fc3468ab7e8eb1be Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 16:15:08 -0700
Subject: [PATCH 4/9] mannWhitney: precompute modality on replicates when
 available

---
 src/common/testVersions/mannWhitney.tsx | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index a2fe44295..7fe5164e0 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -115,11 +115,20 @@ export function precomputeModalityAnalysis(
   isSubtest: boolean,
 ): void {
   for (const result of results) {
-    const analysis = computeModalityAnalysis(
-      result.base_runs ?? [],
-      result.new_runs ?? [],
-      isSubtest,
-    );
+    // Prefer replicates when present — same selection KdeModesPanel and the
+    // chart use in RevisionRowExpandable. Otherwise the precomputed counts
+    // (driving the Mode Δ column and the Distribution Interpretation row)
+    // would run KDE on fewer samples than the blurb, and the two views
+    // would disagree on rows that have rich replicates data.
+    const baseValues =
+      result.base_runs_replicates && result.base_runs_replicates.length
+        ? result.base_runs_replicates
+        : (result.base_runs ?? []);
+    const newValues =
+      result.new_runs_replicates && result.new_runs_replicates.length
+        ? result.new_runs_replicates
+        : (result.new_runs ?? []);
+    const analysis = computeModalityAnalysis(baseValues, newValues, isSubtest);
     result.modeDeltaPct = analysis.largestPeakShiftPct;
     result.baseModeCount = analysis.baseModes.peakLocs.length;
     result.newModeCount = analysis.newModes.peakLocs.length;

From fabd084dd98f0c7c50fc02dde9f2ca248fe9823c Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 16:49:52 -0700
Subject: [PATCH 5/9] =?UTF-8?q?mannWhitney:=20fix=20Mode=20=CE=94=20sort?=
 =?UTF-8?q?=20direction=20=E2=80=94=20DESC=20now=20shows=20biggest=20impro?=
 =?UTF-8?q?vement=20first?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/common/testVersions/mannWhitney.tsx | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 7fe5164e0..4c26802b6 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -178,13 +178,16 @@ export const mannWhitneyStrategy = {
           resultA: MannWhitneyResultsItem,
           resultB: MannWhitneyResultsItem,
         ) {
-          // Normalize sign so positive = "improved" regardless of metric
-          // direction; rows without a computed shift sort as 0.
+          // ASC semantics — useTableSort swaps args for DESC. So in DESC
+          // mode this produces "biggest improvement first" (largest
+          // normalized first); in ASC mode the inverse. The normalization
+          // makes a positive value always mean "improved" regardless of
+          // metric direction; rows without a computed shift sort as 0.
           const normalized = (r: MannWhitneyResultsItem) => {
             const pct = r.modeDeltaPct ?? 0;
             return r.lower_is_better ? -pct : pct;
           };
-          return normalized(resultB) - normalized(resultA);
+          return normalized(resultA) - normalized(resultB);
         },
         tooltip: tooltipModeDelta,
         tooltipIcon: true,

From 2aec513f90836666c1d9a56390fd40e097e1f7d9 Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 19:53:40 -0700
Subject: [PATCH 6/9] =?UTF-8?q?mannWhitney:=20lazy-precompute=20Mode=20?=
 =?UTF-8?q?=CE=94=20analysis=20to=20restore=20load=20speed?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../CompareResults/ResultsTable.test.tsx      | 298 +++++++++---------
 .../SubtestsResultsView.test.tsx              | 100 +++---
 .../OverTimeResultsView.test.tsx.snap         |  10 +-
 .../__snapshots__/ResultsTable.test.tsx.snap  |  24 +-
 .../__snapshots__/ResultsView.test.tsx.snap   |  10 +-
 .../SubtestsResultsView.test.tsx.snap         |  60 ++--
 src/common/constants.ts                       |   2 +-
 src/common/testVersions/mannWhitney.tsx       | 107 ++++---
 .../MannWhitneyCompareMetrics.tsx             |  11 +-
 src/components/CompareResults/loader.ts       |  23 --
 .../CompareResults/overTimeLoader.ts          |  12 -
 .../CompareResults/subtestsLoader.ts          |  13 +-
 .../CompareResults/subtestsOverTimeLoader.tsx |  11 +-
 13 files changed, 330 insertions(+), 351 deletions(-)

diff --git a/src/__tests__/CompareResults/ResultsTable.test.tsx b/src/__tests__/CompareResults/ResultsTable.test.tsx
index e0808db90..5fb5c3adb 100644
--- a/src/__tests__/CompareResults/ResultsTable.test.tsx
+++ b/src/__tests__/CompareResults/ResultsTable.test.tsx
@@ -722,9 +722,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
       '  rev: devilrabbit',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(screen.getByRole('rowgroup')).toMatchSnapshot();
   });
@@ -748,12 +748,12 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await screen.findByText('a11yr');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
 
     expect(summarizeTableFiltersFromUrl()).toEqual({});
@@ -762,9 +762,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Windows/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'linux', 'android', 'ios'],
@@ -775,12 +775,12 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Windows/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
@@ -788,8 +788,8 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Linux/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios'],
@@ -798,9 +798,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Linux/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios', 'linux'],
@@ -809,22 +809,22 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', 'Select all values');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
-      '  - inexistant, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - inexistant, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
     await clickMenuItem(user, 'Platform', /macOS/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['windows', 'linux', 'android', 'ios'],
@@ -833,9 +833,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Android/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['windows', 'linux', 'ios'],
@@ -844,7 +844,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Platform', /Select only.*Android/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Android, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Android, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['android'],
@@ -883,10 +883,10 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await screen.findByText('a11yr');
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
@@ -894,8 +894,8 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /No changes/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['improvement', 'regression'],
@@ -904,7 +904,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Improvement/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -914,9 +914,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['none', 'improvement'],
@@ -925,17 +925,17 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
 
     await clickMenuItem(user, 'Status', /Select only.*Regression/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -944,7 +944,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     await clickMenuItem(user, 'Status', /Select only.*Improvement/);
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['improvement'],
@@ -961,7 +961,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
 
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html spam opt e10s fission stylo webrender',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
     ]);
     const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
     expect(await summarizeTableFiltersFromCheckboxes(user)).toEqual({
@@ -997,26 +997,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
-      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
-      '  - Windows 10, NM, , 1.2, , 99.00 %',
-      '  - Windows 10, NM, , 1.2, , 49.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 1.3, -, 24.00 %',
+      '  - Windows 10, ~0.00 %, , 1.2, , 99.00 %',
+      '  - Windows 10, ~-2.40 %, , 1.2, , 49.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
-      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
-      '  - Windows 10, NM, , 2, , 98.00 %',
-      '  - Windows 10, NM, , 2, , 48.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 2.1, -, 23.00 %',
+      '  - Windows 10, ~0.00 %, , 2, , 98.00 %',
+      '  - Windows 10, ~-2.40 %, , 2, , 48.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
-      '  - Windows 10, NM, , 0.8, , 99.00 %',
-      '  - Windows 10, NM, , 0.8, , 49.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.9, -, 24.00 %',
+      '  - Windows 10, ~0.00 %, , 0.8, , 99.00 %',
+      '  - Windows 10, ~-2.40 %, , 0.8, , 49.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(deltaButton).toMatchSnapshot();
@@ -1028,26 +1028,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
-      '  - Windows 10, NM, , 2, , 48.00 %',
-      '  - Windows 10, NM, , 2, , 98.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 2, -, 43.00 %',
+      '  - Windows 10, ~-2.40 %, , 2, , 48.00 %',
+      '  - Windows 10, ~0.00 %, , 2, , 98.00 %',
       '  rev: spam',
-      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, NM, , 1.2, , 49.00 %',
-      '  - Windows 10, NM, , 1.2, , 99.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, ~-2.40 %, , 1.2, , 49.00 %',
+      '  - Windows 10, ~0.00 %, , 1.2, , 99.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, NM, , 0.8, , 49.00 %',
-      '  - Windows 10, NM, , 0.8, , 99.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, ~-2.40 %, , 0.8, , 49.00 %',
+      '  - Windows 10, ~0.00 %, , 0.8, , 99.00 %',
       '  rev: spam',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
     ]);
     // It should have the "ascending" SVG.
     expect(deltaButton).toMatchSnapshot();
@@ -1062,26 +1062,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
-      '  - Windows 10, NM, , 2, , 98.00 %',
-      '  - Windows 10, NM, , 2, , 48.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 2, -, 43.00 %',
+      '  - Windows 10, ~0.00 %, , 2, , 98.00 %',
+      '  - Windows 10, ~-2.40 %, , 2, , 48.00 %',
       '  rev: spam',
-      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, NM, , 1.2, , 99.00 %',
-      '  - Windows 10, NM, , 1.2, , 49.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, ~0.00 %, , 1.2, , 99.00 %',
+      '  - Windows 10, ~-2.40 %, , 1.2, , 49.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, NM, , 0.8, , 99.00 %',
-      '  - Windows 10, NM, , 0.8, , 49.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, ~0.00 %, , 0.8, , 99.00 %',
+      '  - Windows 10, ~-2.40 %, , 0.8, , 49.00 %',
       '  rev: spam',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(significanceButton).toMatchSnapshot();
@@ -1093,26 +1093,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, NM, , -, , 50.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, NM, , 0.8, , 49.00 %',
-      '  - Windows 10, NM, , 0.8, , 99.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, ~-2.40 %, , 0.8, , 49.00 %',
+      '  - Windows 10, ~0.00 %, , 0.8, , 99.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 0.8, -, 44.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, NM, , 1.2, , 49.00 %',
-      '  - Windows 10, NM, , 1.2, , 99.00 %',
-      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, ~-2.40 %, , 1.2, , 49.00 %',
+      '  - Windows 10, ~0.00 %, , 1.2, , 99.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 1.2, -, 44.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, NM, , 2, , 48.00 %',
-      '  - Windows 10, NM, , 2, , 98.00 %',
-      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
+      '  - Windows 10, ~-2.40 %, , 2, , 48.00 %',
+      '  - Windows 10, ~0.00 %, , 2, , 98.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 2, -, 43.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(significanceButton).toMatchSnapshot();
@@ -1127,26 +1127,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, NM, , -, , 100.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - Windows 10, NM, , -, , 50.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, NM, , 0.8, , 99.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, NM, , 0.8, , 49.00 %',
+      '  - Windows 10, ~0.00 %, , 0.8, , 99.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.9, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 0.8, -, 44.00 %',
+      '  - Windows 10, ~-2.40 %, , 0.8, , 49.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, NM, , 1.2, , 99.00 %',
-      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
-      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
-      '  - Windows 10, NM, , 1.2, , 49.00 %',
+      '  - Windows 10, ~0.00 %, , 1.2, , 99.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 1.3, -, 24.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 1.2, -, 44.00 %',
+      '  - Windows 10, ~-2.40 %, , 1.2, , 49.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, NM, , 2, , 98.00 %',
-      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
-      '  - Windows 10, NM, , 2, , 48.00 %',
+      '  - Windows 10, ~0.00 %, , 2, , 98.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 2.1, -, 23.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 2, -, 43.00 %',
+      '  - Windows 10, ~-2.40 %, , 2, , 48.00 %',
     ]);
 
     expect(effectSizeButton).toMatchSnapshot();
@@ -1158,26 +1158,26 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, NM, , -, , 50.00 %',
-      '  - Linux 18.04, NM, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, NM, , -, , 100.00 %',
+      '  - Windows 10, ~-2.40 %, , -, , 50.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, -, -, 45.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.1, -, 25.00 %',
+      '  - Windows 10, ~0.00 %, , -, , 100.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, NM, , 0.8, , 49.00 %',
-      '  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %',
-      '  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %',
-      '  - Windows 10, NM, , 0.8, , 99.00 %',
+      '  - Windows 10, ~-2.40 %, , 0.8, , 49.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 0.8, -, 44.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 0.9, -, 24.00 %',
+      '  - Windows 10, ~0.00 %, , 0.8, , 99.00 %',
       'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Windows 10, NM, , 1.2, , 49.00 %',
-      '  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %',
-      '  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %',
-      '  - Windows 10, NM, , 1.2, , 99.00 %',
+      '  - Windows 10, ~-2.40 %, , 1.2, , 49.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 1.2, -, 44.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 1.3, -, 24.00 %',
+      '  - Windows 10, ~0.00 %, , 1.2, , 99.00 %',
       '  rev: tictactoe',
-      '  - Windows 10, NM, , 2, , 48.00 %',
-      '  - Linux 18.04, NM, Regression, 2, -, 43.00 %',
-      '  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %',
-      '  - Windows 10, NM, , 2, , 98.00 %',
+      '  - Windows 10, ~-2.40 %, , 2, , 48.00 %',
+      '  - Linux 18.04, ~1.85 %, Regression, 2, -, 43.00 %',
+      '  - macOS 10.15, ~1.08 %, Improvement, 2.1, -, 23.00 %',
+      '  - Windows 10, ~0.00 %, , 2, , 98.00 %',
     ]);
     expect(effectSizeButton).toMatchSnapshot();
     // It should be persisted in the URL
diff --git a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
index 06ab1010f..7e7c516eb 100644
--- a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
@@ -527,11 +527,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting();
       // Initial view (alphabetical ordered, even if "sort by subtests" isn't specified
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: NM, -0.04, -, 15.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
-        'regression.html: NM, 0.12, , 25.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
       ]);
 
       // Sort by Delta
@@ -542,11 +542,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort descending
       await user.click(deltaButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: NM, 0.12, , 25.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
-        'browser.html: NM, -0.04, -, 15.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
       ]);
 
       // It should have the "descending" SVG.
@@ -557,11 +557,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort ascending
       await user.click(deltaButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'tablemutation.html: NM, 0.01, -, 45.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'browser.html: NM, -0.04, -, 15.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
-        'regression.html: NM, 0.12, , 25.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -574,11 +574,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       });
       await user.click(significanceButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: NM, -0.04, -, 15.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'regression.html: NM, 0.12, , 25.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
       ]);
       // It should have the "no sort" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -590,11 +590,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort by Significance ascending
       await user.click(significanceButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'improvement.html: NM, -0.05, , 50.00%',
-        'regression.html: NM, 0.12, , 25.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
-        'browser.html: NM, -0.04, -, 15.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'significance|asc');
 
@@ -604,11 +604,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       });
       await user.click(effectButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'browser.html: NM, -0.04, -, 15.00%',
-        'regression.html: NM, 0.12, , 25.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
       ]);
 
       // It should have the "descending" SVG.
@@ -619,11 +619,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Sort by Effect Size ascending
       await user.click(effectButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'improvement.html: NM, -0.05, , 50.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'regression.html: NM, 0.12, , 25.00%',
-        'browser.html: NM, -0.04, -, 15.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'effects|asc');
     });
@@ -632,11 +632,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting({ extraParameters: 'sort=delta|asc' });
       await screen.findByText('dhtml.html');
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'tablemutation.html: NM, 0.01, -, 45.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'browser.html: NM, -0.04, -, 15.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
-        'regression.html: NM, 0.12, , 25.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -646,11 +646,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await setupForSorting({ extraParameters: 'sort=delta' });
       await screen.findByText('dhtml.html');
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: NM, 0.12, , 25.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
-        'browser.html: NM, -0.04, -, 15.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -659,11 +659,11 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
     it('initializes the sort from the URL at load time for a descending sort', async () => {
       await setupForSorting({ extraParameters: 'sort=delta|desc' });
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
-        'regression.html: NM, 0.12, , 25.00%',
-        'improvement.html: NM, -0.05, , 50.00%',
-        'browser.html: NM, -0.04, -, 15.00%',
-        'dhtml.html: NM, 0.02, , 60.00%',
-        'tablemutation.html: NM, 0.01, -, 45.00%',
+        'regression.html: ~1.04 %, 0.12, , 25.00%',
+        'improvement.html: ~-1.44 %, -0.05, , 50.00%',
+        'browser.html: ~-1.43 %, -0.04, -, 15.00%',
+        'dhtml.html: ~1.14 %, 0.02, , 60.00%',
+        'tablemutation.html: ~0.98 %, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index e06bf3c70..42939ebe6 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -417,7 +417,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
@@ -849,7 +849,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.85 %
                 </div>
                 <div
                   class="status cell"
@@ -1044,7 +1044,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.08 %
                 </div>
                 <div
                   class="status cell"
@@ -1239,7 +1239,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-24.00 %
                 </div>
                 <div
                   class="status cell"
@@ -1434,7 +1434,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-2.40 %
                 </div>
                 <div
                   class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index a103d7925..c575e39e8 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1390,7 +1390,7 @@ exports[`Results Table Should match snapshot 1`] = `
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
@@ -1822,7 +1822,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~1.85 %
                             </div>
                             <div
                               class="status cell"
@@ -2017,7 +2017,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~1.08 %
                             </div>
                             <div
                               class="status cell"
@@ -2212,7 +2212,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~-2.40 %
                             </div>
                             <div
                               class="status cell"
@@ -2494,7 +2494,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~-24.00 %
                             </div>
                             <div
                               class="status cell"
@@ -4312,7 +4312,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
@@ -4744,7 +4744,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~1.85 %
                             </div>
                             <div
                               class="status cell"
@@ -4952,7 +4952,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~1.08 %
                             </div>
                             <div
                               class="status cell"
@@ -5160,7 +5160,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~-2.40 %
                             </div>
                             <div
                               class="status cell"
@@ -5455,7 +5455,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="mode-delta cell"
                               role="cell"
                             >
-                              NM
+                              ~0.00 %
                             </div>
                             <div
                               class="status cell"
@@ -6358,7 +6358,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="mode-delta cell"
         role="cell"
       >
-        NM
+        ~1.08 %
       </div>
       <div
         class="status cell"
@@ -6605,7 +6605,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="mode-delta cell"
         role="cell"
       >
-        NM
+        ~1.08 %
       </div>
       <div
         class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index 398e1446e..46e656977 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -1580,7 +1580,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
@@ -2012,7 +2012,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.85 %
                 </div>
                 <div
                   class="status cell"
@@ -2207,7 +2207,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.08 %
                 </div>
                 <div
                   class="status cell"
@@ -2402,7 +2402,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-24.00 %
                 </div>
                 <div
                   class="status cell"
@@ -2597,7 +2597,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-2.40 %
                 </div>
                 <div
                   class="status cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index 81d68caa8..2ac53d54c 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -992,7 +992,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -1303,7 +1303,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.43 %
                 </div>
                 <div
                   class="status cell"
@@ -1447,7 +1447,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.14 %
                 </div>
                 <div
                   class="status cell"
@@ -1591,7 +1591,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.44 %
                 </div>
                 <div
                   class="status cell"
@@ -1735,7 +1735,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.04 %
                 </div>
                 <div
                   class="status cell"
@@ -1879,7 +1879,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~0.98 %
                 </div>
                 <div
                   class="status cell"
@@ -2938,7 +2938,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -3251,7 +3251,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.43 %
                 </div>
                 <div
                   class="status cell"
@@ -3397,7 +3397,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.14 %
                 </div>
                 <div
                   class="status cell"
@@ -3569,7 +3569,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.44 %
                 </div>
                 <div
                   class="status cell"
@@ -3728,7 +3728,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.04 %
                 </div>
                 <div
                   class="status cell"
@@ -3887,7 +3887,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~0.98 %
                 </div>
                 <div
                   class="status cell"
@@ -4575,7 +4575,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -4888,7 +4888,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.43 %
                 </div>
                 <div
                   class="status cell"
@@ -5034,7 +5034,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.14 %
                 </div>
                 <div
                   class="status cell"
@@ -5206,7 +5206,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.44 %
                 </div>
                 <div
                   class="status cell"
@@ -5365,7 +5365,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.04 %
                 </div>
                 <div
                   class="status cell"
@@ -5524,7 +5524,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~0.98 %
                 </div>
                 <div
                   class="status cell"
@@ -6212,7 +6212,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -6525,7 +6525,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.43 %
                 </div>
                 <div
                   class="status cell"
@@ -6671,7 +6671,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.14 %
                 </div>
                 <div
                   class="status cell"
@@ -6843,7 +6843,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.44 %
                 </div>
                 <div
                   class="status cell"
@@ -7002,7 +7002,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.04 %
                 </div>
                 <div
                   class="status cell"
@@ -7161,7 +7161,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~0.98 %
                 </div>
                 <div
                   class="status cell"
@@ -7849,7 +7849,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -8160,7 +8160,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.43 %
                 </div>
                 <div
                   class="status cell"
@@ -8304,7 +8304,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.14 %
                 </div>
                 <div
                   class="status cell"
@@ -8448,7 +8448,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~-1.44 %
                 </div>
                 <div
                   class="status cell"
@@ -8592,7 +8592,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~1.04 %
                 </div>
                 <div
                   class="status cell"
@@ -8736,7 +8736,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="mode-delta cell"
                   role="cell"
                 >
-                  NM
+                  ~0.98 %
                 </div>
                 <div
                   class="status cell"
diff --git a/src/common/constants.ts b/src/common/constants.ts
index 1134792da..21d9e2e27 100644
--- a/src/common/constants.ts
+++ b/src/common/constants.ts
@@ -338,4 +338,4 @@ export const tooltipConfidence =
 export const tooltipDelta =
   'The percentage difference between the Base and New values';
 export const tooltipModeDelta =
-  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. "NM" (No Modes) means the value could not be computed — typically because there are too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
+  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend\'s median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 4c26802b6..823a23316 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -98,41 +98,68 @@ export function isDistributionNormal(result: MannWhitneyResultsItem): boolean {
 }
 
 /**
- * Precompute the client-side modality analysis for every Mann-Whitney row
- * and attach the relevant fields (`modeDeltaPct`, `baseModeCount`,
- * `newModeCount`) to the result. Called from the data loaders so every UI
- * that talks about modes — the Mode Δ column sort/cell, the Distribution
- * Interpretation row in MannWhitneyCompareMetrics, KdeModesPanel — reads
- * from the same numbers instead of mixing client-side ISJ output with the
- * backend's wider Silverman counts (which used to disagree).
+ * Lazily run (and cache) the client-side modality analysis for a single
+ * row. The first call computes KDE + mode detection + matchModes; every
+ * subsequent call returns immediately. Same lazy strategy as
+ * `getBootstrapCi` for the Sig column — keeps the loader cheap at the
+ * cost of a one-time burst when the user engages with the Mode Δ column.
+ *
+ * Cached fields on the result: `modeDeltaPct`, `baseModeCount`,
+ * `newModeCount`. The presence of `modeDeltaPct !== undefined` is the
+ * "already computed" sentinel (null distinguishes "computed but couldn't
+ * yield a value" — too few samples / no matched pairs).
  *
  * `isSubtest` controls the bandwidth strategy used by KDE: subtest tables
- * use ISJ, top-level tables use the wider SJ approximation. See
- * `bandwidthFor` in kdeAnalysis.ts.
+ * use ISJ, top-level tables use the wider SJ approximation. Pass the same
+ * value the column config's `getColumns(isSubtestTable)` was created with.
  */
-export function precomputeModalityAnalysis(
-  results: MannWhitneyResultsItem[],
+export function ensureModalityAnalysis(
+  result: MannWhitneyResultsItem,
   isSubtest: boolean,
 ): void {
-  for (const result of results) {
-    // Prefer replicates when present — same selection KdeModesPanel and the
-    // chart use in RevisionRowExpandable. Otherwise the precomputed counts
-    // (driving the Mode Δ column and the Distribution Interpretation row)
-    // would run KDE on fewer samples than the blurb, and the two views
-    // would disagree on rows that have rich replicates data.
-    const baseValues =
-      result.base_runs_replicates && result.base_runs_replicates.length
-        ? result.base_runs_replicates
-        : (result.base_runs ?? []);
-    const newValues =
-      result.new_runs_replicates && result.new_runs_replicates.length
-        ? result.new_runs_replicates
-        : (result.new_runs ?? []);
-    const analysis = computeModalityAnalysis(baseValues, newValues, isSubtest);
-    result.modeDeltaPct = analysis.largestPeakShiftPct;
-    result.baseModeCount = analysis.baseModes.peakLocs.length;
-    result.newModeCount = analysis.newModes.peakLocs.length;
+  if (result.modeDeltaPct !== undefined) return;
+  // Prefer replicates when present — same selection KdeModesPanel and the
+  // chart use in RevisionRowExpandable. Otherwise the cached counts /
+  // peak-shift would run KDE on fewer samples than the blurb, and the
+  // Distribution Interpretation row could disagree with the blurb.
+  const baseValues =
+    result.base_runs_replicates && result.base_runs_replicates.length
+      ? result.base_runs_replicates
+      : (result.base_runs ?? []);
+  const newValues =
+    result.new_runs_replicates && result.new_runs_replicates.length
+      ? result.new_runs_replicates
+      : (result.new_runs ?? []);
+  const analysis = computeModalityAnalysis(baseValues, newValues, isSubtest);
+  result.modeDeltaPct = analysis.largestPeakShiftPct;
+  result.baseModeCount = analysis.baseModes.peakLocs.length;
+  result.newModeCount = analysis.newModes.peakLocs.length;
+}
+
+/**
+ * Format the Mode Δ cell text:
+ *   - cached number   → "X.XX %"
+ *   - cached `null`   → "NM"  (modality pipeline ran, no usable pair)
+ *   - uncached        → "~X.XX %" using the backend's `delta_percentage`,
+ *                       prefixed with `~` to signal "approximate, click
+ *                       the column to compute the real Mode Δ"
+ *   - no fallback     → "NM"
+ *
+ * Cell renders run for EVERY row on every render. Triggering the modality
+ * pipeline here would re-introduce the per-row load cost the lazy
+ * refactor removed. So cells stay cheap; the real value populates after
+ * the first sort click via `ensureModalityAnalysis`.
+ */
+function formatModeDelta(result: MannWhitneyResultsItem): string {
+  const cached = result.modeDeltaPct;
+  if (typeof cached === 'number') return `${cached.toFixed(2)} %`;
+  if (cached === null) return 'NM';
+  // Not yet computed — fall back to the backend's median diff percentage.
+  const fallback = result.delta_percentage;
+  if (typeof fallback === 'number' && Number.isFinite(fallback)) {
+    return `~${fallback.toFixed(2)} %`;
   }
+  return 'NM';
 }
 
 export const mannWhitneyStrategy = {
@@ -183,6 +210,13 @@ export const mannWhitneyStrategy = {
           // normalized first); in ASC mode the inverse. The normalization
           // makes a positive value always mean "improved" regardless of
           // metric direction; rows without a computed shift sort as 0.
+          //
+          // First sort-click pays the modality-pipeline cost across all
+          // rows (the comparator is invoked O(n log n) times but each row
+          // is computed only once and cached via `ensureModalityAnalysis`).
+          // Subsequent sorts are free.
+          ensureModalityAnalysis(resultA, isSubtestTable);
+          ensureModalityAnalysis(resultB, isSubtestTable);
           const normalized = (r: MannWhitneyResultsItem) => {
             const pct = r.modeDeltaPct ?? 0;
             return r.lower_is_better ? -pct : pct;
@@ -339,12 +373,7 @@ export const mannWhitneyStrategy = {
           )}
         </div>
         <div className='mode-delta cell' role='cell'>
-          {(() => {
-            const pct = (result as MannWhitneyResultsItem).modeDeltaPct;
-            return pct === null || pct === undefined
-              ? 'NM'
-              : `${pct.toFixed(2)} %`;
-          })()}
+          {formatModeDelta(result as MannWhitneyResultsItem)}
         </div>
         <div className='status cell' role='cell'>
           <Box
@@ -496,21 +525,19 @@ export const mannWhitneyStrategy = {
   },
 
   renderColumns(result: CombinedResultsItemType) {
+    const mwResult = result as MannWhitneyResultsItem;
     const {
       cliffs_delta,
       direction_of_change,
       mann_whitney_test,
       cles,
-      modeDeltaPct,
-    } = result as MannWhitneyResultsItem;
+    } = mwResult;
     const clesValue = cles?.cles ? `${(cles.cles * 100).toFixed(2)} %` : '-';
 
     return (
       <>
         <div className='mode-delta cell' role='cell'>
-          {modeDeltaPct === null || modeDeltaPct === undefined
-            ? 'NM'
-            : `${modeDeltaPct.toFixed(2)} %`}
+          {formatModeDelta(mwResult)}
         </div>
         <div className='status cell' role='cell'>
           <Box
diff --git a/src/components/CompareResults/MannWhitneyCompareMetrics.tsx b/src/components/CompareResults/MannWhitneyCompareMetrics.tsx
index b30d91a8e..1b1a0efa6 100644
--- a/src/components/CompareResults/MannWhitneyCompareMetrics.tsx
+++ b/src/components/CompareResults/MannWhitneyCompareMetrics.tsx
@@ -1,5 +1,6 @@
 import { Box } from '@mui/material';
 
+import { ensureModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import { MannWhitneyResultsItem } from '../../types/state';
 import { getModeInterpretation } from '../../utils/helpers';
 
@@ -52,9 +53,15 @@ export const MannWhitneyCompareMetrics = ({
     result.shapiro_wilk_test_base?.interpretation ?? 'N/A';
   const newShapiroWilkInterpretation =
     result.shapiro_wilk_test_new?.interpretation ?? 'N/A';
-  // Mode counts come from the precomputed client-side modality pipeline
-  // (see precomputeModalityAnalysis), not from the backend's wider-bandwidth
+  // Mode counts come from the client-side modality pipeline (same one
+  // backing the Mode Δ column), not from the backend's wider-bandwidth
   // Silverman KDE — otherwise this row could contradict the Mode Δ column.
+  // We trigger compute on demand here (no-op if a Mode Δ sort already
+  // ran). This only runs for the single expanded row, so the cost is
+  // bounded — unlike eager precompute on every row at load time.
+  // `isSubtest` is derived from base_parent_signature (same trick
+  // RevisionRowExpandable uses) so we pick the same KDE bandwidth.
+  ensureModalityAnalysis(result, result.base_parent_signature !== null);
   const baseMode = result?.baseModeCount ?? null;
   const newMode = result?.newModeCount ?? null;
 
diff --git a/src/components/CompareResults/loader.ts b/src/components/CompareResults/loader.ts
index 679ed20cb..06916b6e6 100644
--- a/src/components/CompareResults/loader.ts
+++ b/src/components/CompareResults/loader.ts
@@ -4,7 +4,6 @@ import {
   compareView,
   MANN_WHITNEY_U,
 } from '../../common/constants';
-import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import {
   fetchCompareResults,
   fetchFakeCompareResults,
@@ -13,7 +12,6 @@ import {
 import {
   Changeset,
   CombinedResultsItemType,
-  MannWhitneyResultsItem,
   Repository,
 } from '../../types/state';
 import { FakeCommitHash, Framework, TestVersion } from '../../types/types';
@@ -199,14 +197,6 @@ export async function loader({ request }: { request: Request }) {
   const useFakeData = url.searchParams.has('fakedata');
   if (useFakeData) {
     const results = await fetchAllFakeCompareResults();
-    // Fake results are Mann-Whitney shaped; precompute the Mode Δ per row
-    // so the column behaves like it would on real backend data.
-    for (const oneRevsResults of results) {
-      precomputeModalityAnalysis(
-        oneRevsResults as unknown as MannWhitneyResultsItem[],
-        false,
-      );
-    }
     // They're all based on the same rev
     const baseRev = results[0][0].base_rev;
     // And the same repository
@@ -302,19 +292,6 @@ export async function getComparisonInformation(
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((results) => {
-    // Precompute the Mode Δ (largest matched-pair peak shift %) per row so
-    // the column can sort without re-running KDE + mode matching per
-    // sortFunction call. Top-level (non-subtest) table → isSubtest=false.
-    if (testVersion === MANN_WHITNEY_U) {
-      for (const oneRevsResults of results) {
-        precomputeModalityAnalysis(
-          oneRevsResults as unknown as MannWhitneyResultsItem[],
-          false,
-        );
-      }
-    }
-    return results;
   });
 
   // TODO what happens if there's no result?
diff --git a/src/components/CompareResults/overTimeLoader.ts b/src/components/CompareResults/overTimeLoader.ts
index 3f123913d..206d04d04 100644
--- a/src/components/CompareResults/overTimeLoader.ts
+++ b/src/components/CompareResults/overTimeLoader.ts
@@ -5,7 +5,6 @@ import {
   compareOverTimeView,
   MANN_WHITNEY_U,
 } from '../../common/constants';
-import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import {
   fetchCompareOverTimeResults,
   memoizedFetchRevisionForRepository,
@@ -13,7 +12,6 @@ import {
 import {
   Changeset,
   CombinedResultsItemType,
-  MannWhitneyResultsItem,
   Repository,
 } from '../../types/state';
 import { Framework, TestVersion, TimeRange } from '../../types/types';
@@ -230,16 +228,6 @@ export async function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((results) => {
-    if (testVersion === MANN_WHITNEY_U) {
-      for (const oneRevsResults of results) {
-        precomputeModalityAnalysis(
-          oneRevsResults as unknown as MannWhitneyResultsItem[],
-          false,
-        );
-      }
-    }
-    return results;
   });
 
   const newRevsInfoPromises = newRevs.map((newRev, i) =>
diff --git a/src/components/CompareResults/subtestsLoader.ts b/src/components/CompareResults/subtestsLoader.ts
index d94c7e785..2e381b7ea 100644
--- a/src/components/CompareResults/subtestsLoader.ts
+++ b/src/components/CompareResults/subtestsLoader.ts
@@ -1,7 +1,6 @@
 import { repoMap, frameworks, MANN_WHITNEY_U } from '../../common/constants';
-import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import { fetchSubtestsCompareResults } from '../../logic/treeherder';
-import { MannWhitneyResultsItem, Repository } from '../../types/state';
+import { Repository } from '../../types/state';
 import { Framework, TestVersion } from '../../types/types';
 
 // This function checks and sanitizes the input values, then returns values that
@@ -187,16 +186,6 @@ export function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((subtestResults) => {
-    // Subtests use ISJ bandwidth (narrower, data-driven) for Mode Δ since
-    // they typically have more samples than top-level aggregated rows.
-    if (testVersion === MANN_WHITNEY_U) {
-      precomputeModalityAnalysis(
-        subtestResults as unknown as MannWhitneyResultsItem[],
-        true,
-      );
-    }
-    return subtestResults;
   });
 
   return {
diff --git a/src/components/CompareResults/subtestsOverTimeLoader.tsx b/src/components/CompareResults/subtestsOverTimeLoader.tsx
index e7d5bb577..906926b21 100644
--- a/src/components/CompareResults/subtestsOverTimeLoader.tsx
+++ b/src/components/CompareResults/subtestsOverTimeLoader.tsx
@@ -4,9 +4,8 @@ import {
   timeRanges,
   MANN_WHITNEY_U,
 } from '../../common/constants';
-import { precomputeModalityAnalysis } from '../../common/testVersions/mannWhitney';
 import { fetchSubtestsCompareOverTimeResults } from '../../logic/treeherder';
-import { MannWhitneyResultsItem, Repository } from '../../types/state';
+import { Repository } from '../../types/state';
 import { Framework, TestVersion, TimeRange } from '../../types/types';
 
 // This function checks and sanitizes the input values, then returns values that
@@ -213,14 +212,6 @@ export function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((subtestResults) => {
-    if (testVersion === MANN_WHITNEY_U) {
-      precomputeModalityAnalysis(
-        subtestResults as unknown as MannWhitneyResultsItem[],
-        true,
-      );
-    }
-    return subtestResults;
   });
 
   return {

From c6abeeb4651a21271d0d34cf47d669706570f346 Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 19:56:26 -0700
Subject: [PATCH 7/9] lint fix

---
 src/common/testVersions/mannWhitney.tsx | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 823a23316..401b4d689 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -526,12 +526,8 @@ export const mannWhitneyStrategy = {
 
   renderColumns(result: CombinedResultsItemType) {
     const mwResult = result as MannWhitneyResultsItem;
-    const {
-      cliffs_delta,
-      direction_of_change,
-      mann_whitney_test,
-      cles,
-    } = mwResult;
+    const { cliffs_delta, direction_of_change, mann_whitney_test, cles } =
+      mwResult;
     const clesValue = cles?.cles ? `${(cles.cles * 100).toFixed(2)} %` : '-';
 
     return (

From 6354698f7cd3884d559462f6db050affebf8c3f4 Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Tue, 21 Jul 2026 18:23:52 -0700
Subject: [PATCH 8/9] replace NM with "No modes"

---
 .../OverTimeResultsView.test.tsx.snap         |  2 +-
 .../__snapshots__/ResultsTable.test.tsx.snap  | 68 +++++++++----------
 .../__snapshots__/ResultsView.test.tsx.snap   |  2 +-
 .../SubtestsResultsView.test.tsx.snap         | 10 +--
 src/common/constants.ts                       |  2 +-
 src/common/testVersions/mannWhitney.tsx       |  8 +--
 6 files changed, 46 insertions(+), 46 deletions(-)

diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index 42939ebe6..63100b1ee 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -417,7 +417,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index c575e39e8..ceac71ad7 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1390,7 +1390,7 @@ exports[`Results Table Should match snapshot 1`] = `
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
@@ -4312,7 +4312,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
@@ -5972,26 +5972,26 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
 [
   "a11yr dhtml.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %",
-  "  - Linux 18.04, NM, Regression, -, -, 45.00 %",
-  "  - Windows 10, NM, , -, , 50.00 %",
-  "  - Windows 10, NM, , -, , 100.00 %",
+  "  - macOS 10.15, No modes, Improvement, 0.1, -, 25.00 %",
+  "  - Linux 18.04, No modes, Regression, -, -, 45.00 %",
+  "  - Windows 10, No modes, , -, , 50.00 %",
+  "  - Windows 10, No modes, , -, , 100.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %",
-  "  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %",
-  "  - Windows 10, NM, , 0.8, , 49.00 %",
-  "  - Windows 10, NM, , 0.8, , 99.00 %",
+  "  - macOS 10.15, No modes, Improvement, 0.9, -, 24.00 %",
+  "  - Linux 18.04, No modes, Regression, 0.8, -, 44.00 %",
+  "  - Windows 10, No modes, , 0.8, , 49.00 %",
+  "  - Windows 10, No modes, , 0.8, , 99.00 %",
   "a11yr aria.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %",
-  "  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %",
-  "  - Windows 10, NM, , 1.2, , 49.00 %",
-  "  - Windows 10, NM, , 1.2, , 99.00 %",
+  "  - macOS 10.15, No modes, Improvement, 1.3, -, 24.00 %",
+  "  - Linux 18.04, No modes, Regression, 1.2, -, 44.00 %",
+  "  - Windows 10, No modes, , 1.2, , 49.00 %",
+  "  - Windows 10, No modes, , 1.2, , 99.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %",
-  "  - Linux 18.04, NM, Regression, 2, -, 43.00 %",
-  "  - Windows 10, NM, , 2, , 48.00 %",
-  "  - Windows 10, NM, , 2, , 98.00 %",
+  "  - macOS 10.15, No modes, Improvement, 2.1, -, 23.00 %",
+  "  - Linux 18.04, No modes, Regression, 2, -, 43.00 %",
+  "  - Windows 10, No modes, , 2, , 48.00 %",
+  "  - Windows 10, No modes, , 2, , 98.00 %",
 ]
 `;
 
@@ -6055,26 +6055,26 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
 [
   "a11yr dhtml.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, NM, Improvement, 0.1, -, 25.00 %",
-  "  - Linux 18.04, NM, Regression, -, -, 45.00 %",
-  "  - Windows 10, NM, , -, , 50.00 %",
-  "  - Windows 10, NM, , -, , 100.00 %",
+  "  - macOS 10.15, No modes, Improvement, 0.1, -, 25.00 %",
+  "  - Linux 18.04, No modes, Regression, -, -, 45.00 %",
+  "  - Windows 10, No modes, , -, , 50.00 %",
+  "  - Windows 10, No modes, , -, , 100.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, NM, Improvement, 0.9, -, 24.00 %",
-  "  - Linux 18.04, NM, Regression, 0.8, -, 44.00 %",
-  "  - Windows 10, NM, , 0.8, , 49.00 %",
-  "  - Windows 10, NM, , 0.8, , 99.00 %",
+  "  - macOS 10.15, No modes, Improvement, 0.9, -, 24.00 %",
+  "  - Linux 18.04, No modes, Regression, 0.8, -, 44.00 %",
+  "  - Windows 10, No modes, , 0.8, , 49.00 %",
+  "  - Windows 10, No modes, , 0.8, , 99.00 %",
   "a11yr aria.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - macOS 10.15, NM, Improvement, 1.3, -, 24.00 %",
-  "  - Linux 18.04, NM, Regression, 1.2, -, 44.00 %",
-  "  - Windows 10, NM, , 1.2, , 49.00 %",
-  "  - Windows 10, NM, , 1.2, , 99.00 %",
+  "  - macOS 10.15, No modes, Improvement, 1.3, -, 24.00 %",
+  "  - Linux 18.04, No modes, Regression, 1.2, -, 44.00 %",
+  "  - Windows 10, No modes, , 1.2, , 49.00 %",
+  "  - Windows 10, No modes, , 1.2, , 99.00 %",
   "  rev: tictactoe",
-  "  - macOS 10.15, NM, Improvement, 2.1, -, 23.00 %",
-  "  - Linux 18.04, NM, Regression, 2, -, 43.00 %",
-  "  - Windows 10, NM, , 2, , 48.00 %",
-  "  - Windows 10, NM, , 2, , 98.00 %",
+  "  - macOS 10.15, No modes, Improvement, 2.1, -, 23.00 %",
+  "  - Linux 18.04, No modes, Regression, 2, -, 43.00 %",
+  "  - Windows 10, No modes, , 2, , 48.00 %",
+  "  - Windows 10, No modes, , 2, , 98.00 %",
 ]
 `;
 
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index 46e656977..b93ff129d 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -1580,7 +1580,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index 2ac53d54c..2f2064ba5 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -992,7 +992,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -2938,7 +2938,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -4575,7 +4575,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -6212,7 +6212,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -7849,7 +7849,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
diff --git a/src/common/constants.ts b/src/common/constants.ts
index 21d9e2e27..dec5f35cf 100644
--- a/src/common/constants.ts
+++ b/src/common/constants.ts
@@ -338,4 +338,4 @@ export const tooltipConfidence =
 export const tooltipDelta =
   'The percentage difference between the Base and New values';
 export const tooltipModeDelta =
-  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend\'s median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "NM" (No Modes) means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
+  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend\'s median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 401b4d689..077591aef 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -139,11 +139,11 @@ export function ensureModalityAnalysis(
 /**
  * Format the Mode Δ cell text:
  *   - cached number   → "X.XX %"
- *   - cached `null`   → "NM"  (modality pipeline ran, no usable pair)
+ *   - cached `null`   → "No modes"  (modality pipeline ran, no usable pair)
  *   - uncached        → "~X.XX %" using the backend's `delta_percentage`,
  *                       prefixed with `~` to signal "approximate, click
  *                       the column to compute the real Mode Δ"
- *   - no fallback     → "NM"
+ *   - no fallback     → "No modes"
  *
  * Cell renders run for EVERY row on every render. Triggering the modality
  * pipeline here would re-introduce the per-row load cost the lazy
@@ -153,13 +153,13 @@ export function ensureModalityAnalysis(
 function formatModeDelta(result: MannWhitneyResultsItem): string {
   const cached = result.modeDeltaPct;
   if (typeof cached === 'number') return `${cached.toFixed(2)} %`;
-  if (cached === null) return 'NM';
+  if (cached === null) return 'No modes';
   // Not yet computed — fall back to the backend's median diff percentage.
   const fallback = result.delta_percentage;
   if (typeof fallback === 'number' && Number.isFinite(fallback)) {
     return `~${fallback.toFixed(2)} %`;
   }
-  return 'NM';
+  return 'No modes';
 }
 
 export const mannWhitneyStrategy = {

From d27d39a5b0bd997be3ee0b5b5ef7f04e9f31d6e9 Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Tue, 21 Jul 2026 19:48:54 -0700
Subject: [PATCH 9/9] use peak magnitude vs shift and simplify tooltip text

---
 .../OverTimeResultsView.test.tsx.snap         |  2 +-
 .../__snapshots__/ResultsTable.test.tsx.snap  |  4 +-
 .../__snapshots__/ResultsView.test.tsx.snap   |  2 +-
 .../SubtestsResultsView.test.tsx.snap         | 10 ++--
 src/common/constants.ts                       |  2 +-
 src/common/testVersions/mannWhitney.tsx       |  2 +-
 src/utils/kdeAnalysis.ts                      | 53 ++++++++++++-------
 7 files changed, 46 insertions(+), 29 deletions(-)

diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index 63100b1ee..b35653ea9 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -417,7 +417,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index ceac71ad7..dccda5540 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1390,7 +1390,7 @@ exports[`Results Table Should match snapshot 1`] = `
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
@@ -4312,7 +4312,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                     role="columnheader"
                   >
                     <span
-                      aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                      aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
                       class="MuiBox-root css-1tkq7a4"
                       data-mui-internal-clone-element="true"
                     >
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index b93ff129d..f99849d63 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -1580,7 +1580,7 @@ exports[`Results View The table should match snapshot and other elements should
         role="columnheader"
       >
         <span
-          aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+          aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
           class="MuiBox-root css-1tkq7a4"
           data-mui-internal-clone-element="true"
         >
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index 2f2064ba5..f7801cfe1 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -992,7 +992,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -2938,7 +2938,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -4575,7 +4575,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -6212,7 +6212,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
@@ -7849,7 +7849,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   role="columnheader"
                 >
                   <span
-                    aria-label="Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend's median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely)."
+                    aria-label="Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won't throw off the result. A positive number means New is higher. A "~" means it's a quick estimate; click the column title to get the exact number. "No modes" means there wasn't enough clear data to measure a shift."
                     class="MuiBox-root css-1tkq7a4"
                     data-mui-internal-clone-element="true"
                   >
diff --git a/src/common/constants.ts b/src/common/constants.ts
index dec5f35cf..c72c00933 100644
--- a/src/common/constants.ts
+++ b/src/common/constants.ts
@@ -338,4 +338,4 @@ export const tooltipConfidence =
 export const tooltipDelta =
   'The percentage difference between the Base and New values';
 export const tooltipModeDelta =
-  'Largest peak shift between the Base and New distributions, expressed as a percentage of the base peak location. Peaks are detected by KDE mode analysis and paired with the modality matcher; the matched pair with the largest absolute shift is shown. Positive values mean the new peak shifted higher. Values prefixed with "~" are the backend\'s median diff percentage shown as an approximation — click the column header to compute the real Mode Δ across all rows. "No modes" means the value could not be computed: too few runs (fewer than 2 per side), KDE could not find any peaks on one or both sides, or no base peak could be paired with a new peak (a path appeared or disappeared entirely).';
+  'Shows how much the main group of results moved from Base to New, as a percent. Runs tend to fall into groups, and this compares the biggest group on each side — so one odd run won\'t throw off the result. A positive number means New is higher. A "~" means it\'s a quick estimate; click the column title to get the exact number. "No modes" means there wasn\'t enough clear data to measure a shift.';
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 077591aef..20a74a234 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -131,7 +131,7 @@ export function ensureModalityAnalysis(
       ? result.new_runs_replicates
       : (result.new_runs ?? []);
   const analysis = computeModalityAnalysis(baseValues, newValues, isSubtest);
-  result.modeDeltaPct = analysis.largestPeakShiftPct;
+  result.modeDeltaPct = analysis.dominantModeShiftPct;
   result.baseModeCount = analysis.baseModes.peakLocs.length;
   result.newModeCount = analysis.newModes.peakLocs.length;
 }
diff --git a/src/utils/kdeAnalysis.ts b/src/utils/kdeAnalysis.ts
index 7ba2d4e2e..3c20507bc 100644
--- a/src/utils/kdeAnalysis.ts
+++ b/src/utils/kdeAnalysis.ts
@@ -148,36 +148,48 @@ export function computeModeInfo(
 export type ModalityAnalysis = {
   baseModes: ModeInfo;
   newModes: ModeInfo;
-  // Largest matched-pair peak shift as % of base peak location; null when
-  // KDE/mode/matching produced nothing usable. See computeModalityAnalysis.
-  largestPeakShiftPct: number | null;
+  // How far the biggest group of runs moved from Base to New, as a % of the
+  // base peak's position. null when there's no trustworthy group to measure
+  // (see computeModalityAnalysis for the exact cases).
+  dominantModeShiftPct: number | null;
 };
 
 export const EMPTY_MODALITY_ANALYSIS: ModalityAnalysis = {
   baseModes: EMPTY_MODE_INFO,
   newModes: EMPTY_MODE_INFO,
-  largestPeakShiftPct: null,
+  dominantModeShiftPct: null,
 };
 
+// Each peak in the KDE curve covers some share of the runs (its "area
+// fraction"); all peaks on one side add up to ~1, i.e. 100% of the runs.
+// A peak must cover at least this share — 10% — to count as a real group of
+// runs. Smaller peaks are treated as noise (a few stray runs) and ignored, so
+// a tiny bump that happens to move a lot can't hijack the reported shift.
+const MODE_AREA_FLOOR = 0.1;
+
 /**
  * Run the full client-side modality pipeline for a base/new pair.
  *
  * Pipeline (same as `KdeModesPanel`): shared bandwidth (max of per-side
  * `bandwidthFor`), `safeKde` both sides, `computeModeInfo` to get peaks +
  * area fractions, `matchModes` to align base/new peaks. Then derives the
- * largest matched-pair peak shift, as a signed percentage of the base peak
- * location (positive = new peak shifted higher).
+ * shift of the dominant matched mode — the pair holding the largest share
+ * of the runs — as a signed percentage of the base peak location (positive =
+ * new peak shifted higher). Picking the biggest group rather than the biggest
+ * mover keeps a small, noisy peak from driving the reported number when the
+ * main peak barely moved.
  *
- * `largestPeakShiftPct` is `null` when:
+ * `dominantModeShiftPct` is `null` when:
  *   - either side has < 2 samples
  *   - either KDE fails (e.g. degenerate inputs)
  *   - mode detection finds no peaks on either side
  *   - no matched pairs (e.g. only unmatched modes — paths appeared/disappeared)
- *   - the only matched base peaks are at exactly zero (can't divide)
+ *   - no matched pair clears MODE_AREA_FLOOR (only noise-level modes)
+ *   - the dominant matched base peak is at exactly zero (can't divide)
  *
  * Mode counts (`baseModes.peakLocs.length` / `newModes.peakLocs.length`)
- * are 0 in the same conditions that drive `largestPeakShiftPct` to null
- * (except the divide-by-zero case, which still yields counts).
+ * are 0 in the same conditions that drive `dominantModeShiftPct` to null
+ * (except the divide-by-zero / below-floor cases, which still yield counts).
  *
  * @param valleyThreshold Passed to `fitModesFromKde`. Defaults to 0.5 to
  *   match `RevisionRowExpandable`'s slider default; the precompute path
@@ -202,7 +214,7 @@ export function computeModalityAnalysis(
   const baseModes = computeModeInfo(bKde.x, bKde.y, valleyThreshold);
   const newModes = computeModeInfo(nKde.x, nKde.y, valleyThreshold);
   if (!baseModes.peakLocs.length || !newModes.peakLocs.length) {
-    return { baseModes, newModes, largestPeakShiftPct: null };
+    return { baseModes, newModes, dominantModeShiftPct: null };
   }
   const { pairs } = matchModes(
     baseModes.peakLocs,
@@ -210,15 +222,20 @@ export function computeModalityAnalysis(
     newModes.peakLocs,
     newModes.fracs,
   );
-  let bestPct: number | null = null;
+  // Report how far the biggest group of runs moved — not whichever peak moved
+  // the most. Each matched pair's "size" is the average share of runs under
+  // its two peaks; pairs smaller than MODE_AREA_FLOOR are noise and skipped.
+  // Of the rest we keep the largest (the dominant group) and use its shift.
+  let dominantModeShiftPct: number | null = null;
+  let bestMag = -Infinity;
   for (const [bi, ni] of pairs) {
     const baseLoc = baseModes.peakLocs[bi];
     const newLoc = newModes.peakLocs[ni];
-    if (baseLoc === 0) continue;
-    const pct = ((newLoc - baseLoc) / baseLoc) * 100;
-    if (bestPct === null || Math.abs(pct) > Math.abs(bestPct)) {
-      bestPct = pct;
-    }
+    if (baseLoc === 0) continue; // can't express the shift as a percentage
+    const mag = (baseModes.fracs[bi] + newModes.fracs[ni]) / 2;
+    if (mag < MODE_AREA_FLOOR || mag <= bestMag) continue;
+    bestMag = mag;
+    dominantModeShiftPct = ((newLoc - baseLoc) / baseLoc) * 100;
   }
-  return { baseModes, newModes, largestPeakShiftPct: bestPct };
+  return { baseModes, newModes, dominantModeShiftPct };
 }