From 13259e76b5ed50ccc92006fa7e6720c664aceb42 Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 17 Jun 2026 17:33:59 -0700
Subject: [PATCH 1/3] mannWhitney: drive Sig column from bootstrap CI

The Sig column, its filter, its sort, and the expanded-row alert now all
read from a single precomputed bootstrap (BCa) CI on the difference of
medians, replacing the Mann-Whitney p-value's `interpretation` string as
the source of truth.
---
 .../CompareResults/ResultsTable.test.tsx      | 246 +++++++++---------
 .../CompareResults/RevisionRow.test.tsx       |  43 ---
 .../SubtestsResultsView.test.tsx              |  60 ++---
 .../SubtestsRevisionRow.test.tsx              |   6 +-
 .../OverTimeResultsView.test.tsx.snap         |  60 ++++-
 .../__snapshots__/ResultsTable.test.tsx.snap  | 183 +++++++++----
 .../__snapshots__/ResultsView.test.tsx.snap   |  86 +++---
 .../SubtestsResultsView.test.tsx.snap         | 135 +---------
 src/common/constants.ts                       |   4 +-
 src/common/testVersions/mannWhitney.tsx       |  69 +++--
 .../CompareResults/PValCliffsDeltaComp.tsx    |  16 +-
 src/components/CompareResults/loader.ts       |  21 ++
 .../CompareResults/overTimeLoader.ts          |  13 +
 .../CompareResults/subtestsLoader.ts          |  13 +-
 .../CompareResults/subtestsOverTimeLoader.tsx |  10 +-
 src/types/state.ts                            |   4 +
 16 files changed, 529 insertions(+), 440 deletions(-)

diff --git a/src/__tests__/CompareResults/ResultsTable.test.tsx b/src/__tests__/CompareResults/ResultsTable.test.tsx
index c663ada1d..4f0e558d9 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, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
       '  rev: devilrabbit',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
     ]);
     expect(screen.getByRole('rowgroup')).toMatchSnapshot();
   });
@@ -748,11 +748,11 @@ 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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - 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 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 50.00 %',
     ]);
 
@@ -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, 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 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'linux', 'android', 'ios'],
@@ -775,11 +775,11 @@ 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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - 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 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 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, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - macOS 10.15, 1.078 %, 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, 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 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios', 'linux'],
@@ -809,11 +809,11 @@ 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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - 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 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
@@ -821,9 +821,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
@@ -833,8 +833,8 @@ 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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
@@ -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, 1.078 %, Improvement, 0.1, , 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['android'],
@@ -883,9 +883,9 @@ 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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 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, 1.849 %, Regression, -, , 45.00 %',
+      '  - macOS 10.15, 1.078 %, 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, 1.849 %, Regression, -, , 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -914,8 +914,8 @@ 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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
@@ -925,9 +925,9 @@ 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',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
       '  - Windows 10, -2.401 %, , -, , 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
@@ -935,7 +935,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     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, 1.849 %, 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, 1.078 %, 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, 1.078 %, Improvement, 0.1, , 25.00 %',
     ]);
     const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
     expect(await summarizeTableFiltersFromCheckboxes(user)).toEqual({
@@ -997,25 +997,25 @@ 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: spam',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, -, 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, -, 24.00 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, , 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, , 24.00 %',
+      '  - Windows 10, -, , 1.2, -, 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 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, , 43.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, , 23.00 %',
+      '  - Windows 10, -, , 2, -, 98.00 %',
       '  - Windows 10, -2.401 %, , 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 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - 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 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, , 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, , 24.00 %',
+      '  - Windows 10, -, , 0.8, -, 99.00 %',
       '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
     ]);
     // It should have the "descending" SVG.
@@ -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, 1.078 %, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
+      '  - 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 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
+      '  - 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 %',
+      '  - 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 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
+      '  - 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 %',
+      '  - 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 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
+      '  - 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 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
       '  - Windows 10, -2.401 %, , -, , 50.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
+      '  - Windows 10, -, , -, -, 100.00 %',
     ]);
     // It should have the "ascending" SVG.
     expect(deltaButton).toMatchSnapshot();
@@ -1060,28 +1060,28 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     });
     await user.click(significanceButton);
     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, , 98.00 %',
-      '  - Windows 10, -2.401 %, , 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 %',
-      '  - Windows 10, -, , 1.2, , 99.00 %',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
       '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, -, , -, -, 100.00 %',
       '  rev: tictactoe',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, -, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, -, 44.00 %',
-      '  - Windows 10, -, , 0.8, , 99.00 %',
       '  - 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, -, 99.00 %',
+      'a11yr aria.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
-      '  - Windows 10, -, , -, , 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - 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, -, 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, -, 98.00 %',
     ]);
     // 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, -, , -, -, 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 %',
-      '  - 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, -, , 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 %',
-      '  - 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, -, , 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 %',
-      '  - 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, -, 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 %',
-      '  - Windows 10, -, , 2, , 98.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, -, 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, -, 43.00 %',
     ]);
     // It should have the "descending" SVG.
     expect(significanceButton).toMatchSnapshot();
@@ -1127,25 +1127,25 @@ 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, 1.078 %, Improvement, 0.1, -, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %',
+      '  - 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 %',
       '  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, -, , 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 %',
       '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, -, , 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 %',
       '  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, -, 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 %',
     ]);
 
@@ -1159,25 +1159,25 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
       '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, -, , -, , 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
+      '  - macOS 10.15, 1.078 %, 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, , 99.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, , 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, , 24.00 %',
+      '  - Windows 10, -, , 0.8, -, 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, , 99.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, , 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, , 24.00 %',
+      '  - Windows 10, -, , 1.2, -, 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, , 98.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, , 43.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, , 23.00 %',
+      '  - Windows 10, -, , 2, -, 98.00 %',
     ]);
     expect(effectSizeButton).toMatchSnapshot();
     // It should be persisted in the URL
diff --git a/src/__tests__/CompareResults/RevisionRow.test.tsx b/src/__tests__/CompareResults/RevisionRow.test.tsx
index ae86e4950..887545ff0 100644
--- a/src/__tests__/CompareResults/RevisionRow.test.tsx
+++ b/src/__tests__/CompareResults/RevisionRow.test.tsx
@@ -281,49 +281,6 @@ describe('Expanded row', () => {
     expect(cliffsDeltaHeader).toBeInTheDocument();
   });
 
-  it('should display mann_whitney_test.interpretation for significance for mann-whitney-u testVersion', async () => {
-    const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
-    const { testCompareMannWhitneyData: rowData } = getTestData();
-
-    renderWithRoute(
-      <RevisionRow
-        result={rowData[0]}
-        view={compareView}
-        gridTemplateColumns='none'
-        replicates={false}
-        testVersion='mann-whitney-u'
-        expandAll={false}
-      />,
-    );
-
-    const expandRowButton = await screen.findByTestId(/ExpandMoreIcon/);
-    await user.click(expandRowButton);
-
-    const notSignificant = await screen.findAllByText(/Not significant/);
-    expect(notSignificant[0]).toBeInTheDocument();
-  });
-
-  it('should handle empty mann_whitney_test.interpretation for significance for mann-whitney-u testVersion', async () => {
-    const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
-    const { testCompareMannWhitneyData: rowData } = getTestData();
-    const resultNoInterpretation = { ...rowData[0], mann_whitney_test: null };
-    renderWithRoute(
-      <RevisionRow
-        result={resultNoInterpretation}
-        view={compareView}
-        gridTemplateColumns='none'
-        replicates={false}
-        testVersion='mann-whitney-u'
-        expandAll={false}
-      />,
-    );
-
-    const expandRowButton = await screen.findByTestId(/ExpandMoreIcon/);
-    await user.click(expandRowButton);
-    const emptySignificant = await screen.findAllByText(/-/);
-    expect(emptySignificant[0]).toBeInTheDocument();
-  });
-
   it('should display median diff and 95% CI alerts when base/new runs are present', async () => {
     const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
     const { testCompareMannWhitneyData: rowData } = getTestData();
diff --git a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
index 87e1b9081..212640cdb 100644
--- a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
@@ -528,9 +528,9 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // 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%',
+        '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%',
       ]);
 
@@ -542,10 +542,10 @@ 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%',
+        '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%',
+        'dhtml.html: 1.135 %, 0.02, -, 60.00%',
         'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
       ]);
 
@@ -558,10 +558,10 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       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%',
+        '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%',
+        'improvement.html: 0.963 %, -0.05, -, 50.00%',
+        'regression.html: 1.135 %, 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([
+        '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: 0.963 %, -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%',
       ]);
       // It should have the "no sort" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -590,10 +590,10 @@ 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%',
+        '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: 0.963 %, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'significance|asc');
@@ -605,10 +605,10 @@ 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%',
+        '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%',
+        'improvement.html: 0.963 %, -0.05, -, 50.00%',
       ]);
 
       // It should have the "descending" SVG.
@@ -619,10 +619,10 @@ 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%',
+        '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%',
+        'dhtml.html: 1.135 %, 0.02, -, 60.00%',
+        'regression.html: 1.135 %, 0.12, -, 25.00%',
         'browser.html: 0.963 %, -0.04, -, 15.00%',
       ]);
       expectParameterToHaveValue('sort', 'effects|asc');
@@ -633,10 +633,10 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       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%',
+        '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%',
+        'improvement.html: 0.963 %, -0.05, -, 50.00%',
+        'regression.html: 1.135 %, 0.12, -, 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -646,10 +646,10 @@ 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%',
+        '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%',
+        'dhtml.html: 1.135 %, 0.02, -, 60.00%',
         'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
@@ -659,10 +659,10 @@ 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%',
+        '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%',
+        'dhtml.html: 1.135 %, 0.02, -, 60.00%',
         'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
       ]);
       // It should have the "descending" SVG.
diff --git a/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx b/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
index d8941e030..adfbf5770 100644
--- a/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
@@ -193,8 +193,12 @@ describe('SubtestsRevisionRow Component', () => {
     const effects = roles[7]?.childNodes[0];
     expect(effects).toHaveTextContent('60.00%');
 
+    // The fixture runs don't yield a CI that excludes 0 once precomputed by
+    // the loader, so this row renders the "-" placeholder. This test mounts
+    // the row directly without the loader, leaving bootstrapCi undefined,
+    // which also falls back to "-". Either way: no icon is rendered.
     const significanceCell = roles[8];
-    expect(significanceCell?.querySelector('svg')).not.toBeNull();
+    expect(significanceCell).toHaveTextContent('-');
 
     const cliffs_delta = roles[6]?.childNodes[1];
     expect(cliffs_delta).toHaveTextContent('0.02');
diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index dbd059e14..78d7450be 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -824,7 +824,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
@@ -1023,7 +1036,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
@@ -1222,7 +1248,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
@@ -1421,7 +1460,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index 95b362d3d..3d6fe6413 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1797,7 +1797,20 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              -
+                              <svg
+                                aria-hidden="true"
+                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                                data-testid="KeyboardDoubleArrowUpIcon"
+                                focusable="false"
+                                viewBox="0 0 24 24"
+                              >
+                                <path
+                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                                />
+                                <path
+                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                                />
+                              </svg>
                             </div>
                             <div
                               class="total-runs cell"
@@ -1996,7 +2009,20 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              -
+                              <svg
+                                aria-hidden="true"
+                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                                data-testid="KeyboardDoubleArrowUpIcon"
+                                focusable="false"
+                                viewBox="0 0 24 24"
+                              >
+                                <path
+                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                                />
+                                <path
+                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                                />
+                              </svg>
                             </div>
                             <div
                               class="total-runs cell"
@@ -2195,7 +2221,20 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              -
+                              <svg
+                                aria-hidden="true"
+                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                                data-testid="KeyboardDoubleArrowUpIcon"
+                                focusable="false"
+                                viewBox="0 0 24 24"
+                              >
+                                <path
+                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                                />
+                                <path
+                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                                />
+                              </svg>
                             </div>
                             <div
                               class="total-runs cell"
@@ -2481,7 +2520,20 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              -
+                              <svg
+                                aria-hidden="true"
+                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                                data-testid="KeyboardDoubleArrowUpIcon"
+                                focusable="false"
+                                viewBox="0 0 24 24"
+                              >
+                                <path
+                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                                />
+                                <path
+                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                                />
+                              </svg>
                             </div>
                             <div
                               class="total-runs cell"
@@ -4693,7 +4745,20 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              -
+                              <svg
+                                aria-hidden="true"
+                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                                data-testid="KeyboardDoubleArrowUpIcon"
+                                focusable="false"
+                                viewBox="0 0 24 24"
+                              >
+                                <path
+                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                                />
+                                <path
+                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                                />
+                              </svg>
                             </div>
                             <div
                               class="total-runs cell"
@@ -4905,7 +4970,20 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              -
+                              <svg
+                                aria-hidden="true"
+                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                                data-testid="KeyboardDoubleArrowUpIcon"
+                                focusable="false"
+                                viewBox="0 0 24 24"
+                              >
+                                <path
+                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                                />
+                                <path
+                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                                />
+                              </svg>
                             </div>
                             <div
                               class="total-runs cell"
@@ -5399,20 +5477,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              -
                             </div>
                             <div
                               class="total-runs cell"
@@ -5835,25 +5900,25 @@ 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 %",
-  "  - Windows 10, -, , -, , 100.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %",
+  "  - 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 %",
-  "  - Windows 10, -, , 0.8, , 99.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 0.8, , 44.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 0.9, , 24.00 %",
+  "  - Windows 10, -, , 0.8, -, 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 %",
-  "  - Windows 10, -, , 1.2, , 99.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 1.2, , 44.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 1.3, , 24.00 %",
+  "  - Windows 10, -, , 1.2, -, 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 %",
-  "  - Windows 10, -, , 2, , 98.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 2, , 43.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 2.1, , 23.00 %",
+  "  - Windows 10, -, , 2, -, 98.00 %",
   "  - Windows 10, -2.401 %, , 2, , 48.00 %",
 ]
 `;
@@ -5908,25 +5973,25 @@ 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 %",
-  "  - Windows 10, -, , -, , 100.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 0.1, -, 25.00 %",
-  "  - Linux 18.04, 1.849 %, Regression, -, -, 45.00 %",
+  "  - 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 %",
-  "  - 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, -, , 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 %",
-  "  - 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, -, , 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 %",
-  "  - 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, -, 98.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 2.1, , 23.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 2, , 43.00 %",
 ]
 `;
 
@@ -6231,7 +6296,20 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="significance cell"
         role="cell"
       >
-        -
+        <svg
+          aria-hidden="true"
+          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+          data-testid="KeyboardDoubleArrowUpIcon"
+          focusable="false"
+          viewBox="0 0 24 24"
+        >
+          <path
+            d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+          />
+          <path
+            d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+          />
+        </svg>
       </div>
       <div
         class="total-runs cell"
@@ -6482,7 +6560,20 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="significance cell"
         role="cell"
       >
-        -
+        <svg
+          aria-hidden="true"
+          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+          data-testid="KeyboardDoubleArrowUpIcon"
+          focusable="false"
+          viewBox="0 0 24 24"
+        >
+          <path
+            d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+          />
+          <path
+            d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+          />
+        </svg>
       </div>
       <div
         class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index fabd553d6..15b655c1f 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -204,19 +204,6 @@ exports[`Results View Should display Base, New and Common graphs with replicates
                     style="padding: 2px;"
                   />
                 </tr>
-                <tr>
-                  <td
-                    style="padding: 2px;"
-                  >
-                    Significance (p-value)
-                  </td>
-                  <td
-                    style="padding: 2px;"
-                  />
-                  <td
-                    style="padding: 2px;"
-                  />
-                </tr>
                 <tr>
                   <td
                     style="padding: 2px;"
@@ -749,19 +736,6 @@ exports[`Results View Should display Base, New and Common graphs with tooltips 1
                     style="padding: 2px;"
                   />
                 </tr>
-                <tr>
-                  <td
-                    style="padding: 2px;"
-                  >
-                    Significance (p-value)
-                  </td>
-                  <td
-                    style="padding: 2px;"
-                  />
-                  <td
-                    style="padding: 2px;"
-                  />
-                </tr>
                 <tr>
                   <td
                     style="padding: 2px;"
@@ -1979,7 +1953,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
@@ -2178,7 +2165,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
@@ -2377,7 +2377,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
@@ -2576,7 +2589,20 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  <svg
+                    aria-hidden="true"
+                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
+                    data-testid="KeyboardDoubleArrowUpIcon"
+                    focusable="false"
+                    viewBox="0 0 24 24"
+                  >
+                    <path
+                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
+                    />
+                    <path
+                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
+                    />
+                  </svg>
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index 18f8b99f1..f5c28e517 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -3267,20 +3267,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -3430,20 +3417,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -3593,20 +3567,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -4869,20 +4830,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -5032,20 +4980,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -5195,20 +5130,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -6471,20 +6393,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -6634,20 +6543,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
@@ -6797,20 +6693,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  -
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/common/constants.ts b/src/common/constants.ts
index cdafa0247..dfb4aea28 100644
--- a/src/common/constants.ts
+++ b/src/common/constants.ts
@@ -324,9 +324,9 @@ export const MANN_WHITNEY_U = 'mann-whitney-u' as TestVersion;
 export const STUDENT_T = 'student-t' as TestVersion;
 
 export const tooltipSignificance =
-  'Significance of the comparison as determined by a Mann Whitney U test. A significant comparison has a p-value of less than 0.05.';
+  'Significance of the comparison as determined by a 95% bootstrap (BCa) confidence interval on the difference of medians. A comparison is significant when the interval excludes zero.';
 export const tooltipStatusMannWhitney =
-  'An improvement or regression being shown here means that the effect size is meaningful, and the difference has a significant p-value.';
+  'An improvement or regression being shown here means that the effect size is meaningful and the difference is statistically significant.';
 export const tooltipTotalRuns =
   'The total number of tasks/jobs that ran for this metric.';
 export const tooltipBaseMean =
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index c83f550cd..a2eb9ead7 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -102,6 +102,29 @@ export function isDistributionNormal(result: MannWhitneyResultsItem): boolean {
   return checkDistributionNormality(result) !== 'neither';
 }
 
+/**
+ * Precompute the bootstrap (BCa)[see src/utils/bootstrap-ci.ts#L163-L203] CI for the difference of medians on every
+ * Mann-Whitney result and attach it to `result.bootstrapCi`. Called from the
+ * data loaders so the Sig column's filter/sort and the expanded-row alert can
+ * read a precomputed value instead of triggering bootstrapMedianDiffCI per
+ * row per render (BCa is ~10–30 ms/row and would tank sort interactions).
+ *
+ * Rows without enough data (< 2 samples on either side) get `bootstrapCi:
+ * null`; the column code treats that as "not significant".
+ */
+export function precomputeMannWhitneyCI(
+  results: MannWhitneyResultsItem[],
+): void {
+  for (const result of results) {
+    const baseRuns = result.base_runs ?? [];
+    const newRuns = result.new_runs ?? [];
+    result.bootstrapCi =
+      baseRuns.length >= 2 && newRuns.length >= 2
+        ? bootstrapMedianDiffCI(baseRuns, newRuns)
+        : null;
+  }
+}
+
 export const mannWhitneyStrategy = {
   getColumns(isSubtestTable: boolean): TableConfig {
     const platformConfig = isSubtestTable
@@ -231,16 +254,26 @@ export const mannWhitneyStrategy = {
           },
         ],
         matchesFunction(result: MannWhitneyResultsItem, valueKey: string) {
-          return result.mann_whitney_test?.interpretation === valueKey;
+          // Significance comes from the precomputed bootstrap CI (see
+          // precomputeMannWhitneyCI above).
+          // Missing CI ⇒ treat as not-significant.
+          const isSig = result.bootstrapCi?.significant ?? false;
+          return (isSig ? 'significant' : 'not significant') === valueKey;
         },
         sortFunction(
           resultA: MannWhitneyResultsItem,
           resultB: MannWhitneyResultsItem,
         ) {
-          return (
-            Math.abs(resultA.mann_whitney_test?.pvalue ?? 0) -
-            Math.abs(resultB.mann_whitney_test?.pvalue ?? 0)
-          );
+          // ASC semantics — useTableSort swaps args for DESC. So in DESC mode
+          // this produces "significant first, then |medianDiff| desc"; in ASC
+          // mode the inverse. Significance is the primary key, magnitude the
+          // tie-breaker so the biggest changes float to the top of each group.
+          const sigA = resultA.bootstrapCi?.significant ?? false;
+          const sigB = resultB.bootstrapCi?.significant ?? false;
+          if (sigA !== sigB) return sigA ? 1 : -1;
+          const magA = Math.abs(resultA.bootstrapCi?.medianDiff ?? 0);
+          const magB = Math.abs(resultB.bootstrapCi?.medianDiff ?? 0);
+          return magA - magB;
         },
       },
 
@@ -267,9 +300,9 @@ export const mannWhitneyStrategy = {
     const {
       test,
       cliffs_delta,
-      mann_whitney_test,
       cles,
       direction_of_change,
+      bootstrapCi,
       base_measurement_unit: baseUnit,
       new_measurement_unit: newUnit,
       base_app: baseApp,
@@ -363,7 +396,7 @@ export const mannWhitneyStrategy = {
           {clesVal ? `${clesVal}% ` : '-'}
         </div>
         <div className='significance cell' role='cell'>
-          {mann_whitney_test?.interpretation === 'significant' ? (
+          {bootstrapCi?.significant ? (
             <KeyboardDoubleArrowUpIcon fontSize='small' />
           ) : (
             '-'
@@ -403,17 +436,19 @@ export const mannWhitneyStrategy = {
       mann_whitney_u_cles: '',
     };
     const { cliffs_delta, cliffs_interpretation } = mwResult;
-    const pValue = mwResult.mann_whitney_test?.pvalue;
-    const p_value_cles = mwResult.mann_whitney_test?.interpretation
-      ? capitalize(mwResult.mann_whitney_test.interpretation)
-      : '';
 
+    // Prefer the precomputed CI populated by the loader. Fall back to an
+    // inline compute for backwards compatibility (e.g. tests that mount the
+    // strategy without going through a loader, or stale results without the
+    // field).
     const baseRuns = mwResult.base_runs ?? [];
     const newRuns = mwResult.new_runs ?? [];
     const ci =
-      baseRuns.length > 0 && newRuns.length > 0
-        ? bootstrapMedianDiffCI(baseRuns, newRuns)
-        : null;
+      mwResult.bootstrapCi !== undefined
+        ? mwResult.bootstrapCi
+        : baseRuns.length > 0 && newRuns.length > 0
+          ? bootstrapMedianDiffCI(baseRuns, newRuns)
+          : null;
     const rawUnit =
       mwResult.base_measurement_unit ?? mwResult.new_measurement_unit ?? 'ms';
     const { fmt, displayUnit } = ci
@@ -453,8 +488,6 @@ export const mannWhitneyStrategy = {
         <PValCliffsDeltaComp
           cliffs_delta={cliffs_delta}
           cliffs_interpretation={cliffs_interpretation}
-          pValue={pValue}
-          p_value_cles={p_value_cles}
           cles={cles}
           cles_direction={cles_direction}
         />
@@ -483,8 +516,8 @@ export const mannWhitneyStrategy = {
     const {
       cliffs_delta,
       direction_of_change,
-      mann_whitney_test,
       cles,
+      bootstrapCi,
       base_standard_stats,
       new_standard_stats,
     } = result as MannWhitneyResultsItem;
@@ -551,7 +584,7 @@ export const mannWhitneyStrategy = {
           {clesValue}
         </div>
         <div className='significance cell' role='cell'>
-          {mann_whitney_test?.interpretation === 'significant' ? (
+          {bootstrapCi?.significant ? (
             <KeyboardDoubleArrowUpIcon fontSize='small' />
           ) : (
             '-'
diff --git a/src/components/CompareResults/PValCliffsDeltaComp.tsx b/src/components/CompareResults/PValCliffsDeltaComp.tsx
index a430b63ac..9465d825f 100644
--- a/src/components/CompareResults/PValCliffsDeltaComp.tsx
+++ b/src/components/CompareResults/PValCliffsDeltaComp.tsx
@@ -5,21 +5,12 @@ import { capitalize } from '../../utils/helpers';
 interface PValCliffsDeltaCompProps {
   cliffs_delta: number;
   cliffs_interpretation: string;
-  pValue: number | undefined | null;
-  p_value_cles: string;
   cles: number | string;
   cles_direction: string;
 }
 
 function PValCliffsDeltaComp(props: PValCliffsDeltaCompProps) {
-  const {
-    cliffs_delta,
-    cliffs_interpretation,
-    pValue,
-    p_value_cles,
-    cles,
-    cles_direction,
-  } = props;
+  const { cliffs_delta, cliffs_interpretation, cles, cles_direction } = props;
   return (
     <Box
       sx={{
@@ -47,11 +38,6 @@ function PValCliffsDeltaComp(props: PValCliffsDeltaCompProps) {
               {capitalize(cliffs_interpretation ?? '')}
             </td>
           </tr>
-          <tr>
-            <td style={{ padding: 2 }}>Significance (p-value)</td>
-            <td style={{ padding: 2 }}>{pValue}</td>
-            <td style={{ padding: 2 }}>{p_value_cles}</td>
-          </tr>
           <tr>
             <td style={{ padding: 2 }}>CLES</td>
             <td style={{ padding: 2 }}>{cles}</td>
diff --git a/src/components/CompareResults/loader.ts b/src/components/CompareResults/loader.ts
index 06916b6e6..81fc998d1 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 { precomputeMannWhitneyCI } 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 +199,13 @@ 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 CI per row so the
+    // Sig column behaves the same way as it would on real backend data.
+    for (const oneRevsResults of results) {
+      precomputeMannWhitneyCI(
+        oneRevsResults as unknown as MannWhitneyResultsItem[],
+      );
+    }
     // They're all based on the same rev
     const baseRev = results[0][0].base_rev;
     // And the same repository
@@ -292,6 +301,18 @@ export async function getComparisonInformation(
     replicates,
     testVersion,
     silvermanKDEEnabled,
+  }).then((results) => {
+    // Precompute the bootstrap CI per row when the data is Mann-Whitney —
+    // the Sig column sorts/filters on it and the expanded-row alert reads it
+    // too, so doing the heavy BCa [see src/utils/bootstrap-ci.ts#L163-L203] work once here avoids per-render thrashing.
+    if (testVersion === MANN_WHITNEY_U) {
+      for (const oneRevsResults of results) {
+        precomputeMannWhitneyCI(
+          oneRevsResults as unknown as MannWhitneyResultsItem[],
+        );
+      }
+    }
+    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..d4704c8b4 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 { precomputeMannWhitneyCI } 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 +230,17 @@ export async function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
+  }).then((results) => {
+    // Same precompute as the main loader so the Sig column has a precomputed
+    // CI to sort/filter on without recomputing per render.
+    if (testVersion === MANN_WHITNEY_U) {
+      for (const oneRevsResults of results) {
+        precomputeMannWhitneyCI(
+          oneRevsResults as unknown as MannWhitneyResultsItem[],
+        );
+      }
+    }
+    return results;
   });
 
   const newRevsInfoPromises = newRevs.map((newRev, i) =>
diff --git a/src/components/CompareResults/subtestsLoader.ts b/src/components/CompareResults/subtestsLoader.ts
index 2e381b7ea..bff1098ab 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 { precomputeMannWhitneyCI } 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) => {
+    // Precompute the bootstrap CI for the Sig column when these are
+    // Mann-Whitney results. Subtests return a flat array (one entry per
+    // subtest), not the per-revision nesting the main loader has.
+    if (testVersion === MANN_WHITNEY_U) {
+      precomputeMannWhitneyCI(
+        subtestResults as unknown as MannWhitneyResultsItem[],
+      );
+    }
+    return subtestResults;
   });
 
   return {
diff --git a/src/components/CompareResults/subtestsOverTimeLoader.tsx b/src/components/CompareResults/subtestsOverTimeLoader.tsx
index 906926b21..a9edd4b9f 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 { precomputeMannWhitneyCI } 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 +213,13 @@ export function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
+  }).then((subtestResults) => {
+    if (testVersion === MANN_WHITNEY_U) {
+      precomputeMannWhitneyCI(
+        subtestResults as unknown as MannWhitneyResultsItem[],
+      );
+    }
+    return subtestResults;
   });
 
   return {
diff --git a/src/types/state.ts b/src/types/state.ts
index 2091e09ef..b37182295 100644
--- a/src/types/state.ts
+++ b/src/types/state.ts
@@ -242,6 +242,10 @@ export type MannWhitneyResultsItem = {
   is_meaningful: boolean | null;
   more_runs_are_needed: boolean | null;
   warning_c_delta?: string | null;
+  // Bootstrap (BCa) [see src/utils/bootstrap-ci.ts#L163-L203] CI for the difference of medians.
+  // `null` means the CI couldn't be computed (e.g.
+  // missing base_runs/new_runs); callers treat that as "not significant".
+  bootstrapCi?: import('../utils/bootstrap-ci').BootstrapCI | 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.

From cb2f1cbf5152ffa38f4b6a38463785ce71d1a639 Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 14:45:37 -0700
Subject: [PATCH 2/3] mannWhitney: render Sig column as S/NS text instead of
 arrow icon

---
 .../CompareResults/ResultsTable.test.tsx      | 300 +++++++++---------
 .../SubtestsResultsView.test.tsx              | 100 +++---
 .../SubtestsRevisionRow.test.tsx              |   8 +-
 .../OverTimeResultsView.test.tsx.snap         |  60 +---
 .../__snapshots__/ResultsTable.test.tsx.snap  | 201 +++---------
 .../__snapshots__/ResultsView.test.tsx.snap   |  60 +---
 .../SubtestsResultsView.test.tsx.snap         |  50 +--
 src/common/constants.ts                       |   2 +-
 src/common/testVersions/mannWhitney.tsx       |  17 +-
 9 files changed, 284 insertions(+), 514 deletions(-)

diff --git a/src/__tests__/CompareResults/ResultsTable.test.tsx b/src/__tests__/CompareResults/ResultsTable.test.tsx
index 4f0e558d9..9e8d4f7d4 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, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
       '  rev: devilrabbit',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - inexistant, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - inexistant, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 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, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - inexistant, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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, 1.078 %, Improvement, 0.1, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 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, 1.849 %, Regression, -, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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, 1.849 %, Regression, -, S, 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, 1.078 %, Improvement, 0.1, S, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['improvement'],
@@ -961,12 +961,12 @@ 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, 1.078 %, Improvement, 0.1, S, 25.00 %',
     ]);
     const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
     expect(await summarizeTableFiltersFromCheckboxes(user)).toEqual({
       'Platform(2)': ['macOS', 'Android'],
-      'Sig(2)': ['Significant', 'Not Significant-'],
+      'Sig(2)': ['SignificantS', 'Not SignificantNS'],
       'Status(3)': ['No changes', 'Improvement', 'Regression'],
     });
 
@@ -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 %',
-      '  - Windows 10, -, , 1.2, -, 99.00 %',
-      '  - Windows 10, -2.401 %, , 1.2, , 49.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
+      '  - Windows 10, -, , 1.2, NS, 99.00 %',
+      '  - Windows 10, -2.401 %, , 1.2, S, 49.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, 1.849 %, Regression, 2, , 43.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, , 23.00 %',
-      '  - Windows 10, -, , 2, -, 98.00 %',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %',
+      '  - Windows 10, -, , 2, NS, 98.00 %',
+      '  - Windows 10, -2.401 %, , 2, S, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 50.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, , 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, , 24.00 %',
-      '  - Windows 10, -, , 0.8, -, 99.00 %',
-      '  - Windows 10, -2.401 %, , 0.8, , 49.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
+      '  - Windows 10, -, , 0.8, NS, 99.00 %',
+      '  - Windows 10, -2.401 %, , 0.8, S, 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, 1.078 %, Improvement, 2.1, , 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, , 43.00 %',
-      '  - Windows 10, -2.401 %, , 2, , 48.00 %',
-      '  - Windows 10, -, , 2, -, 98.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
+      '  - Windows 10, -2.401 %, , 2, S, 48.00 %',
+      '  - Windows 10, -, , 2, NS, 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 %',
-      '  - Windows 10, -, , 1.2, -, 99.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
+      '  - Windows 10, -2.401 %, , 1.2, S, 49.00 %',
+      '  - Windows 10, -, , 1.2, NS, 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 %',
-      '  - Windows 10, -, , 0.8, -, 99.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
+      '  - Windows 10, -2.401 %, , 0.8, S, 49.00 %',
+      '  - Windows 10, -, , 0.8, NS, 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 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 50.00 %',
+      '  - Windows 10, -, , -, NS, 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 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, -, , -, -, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 50.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 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, -, 99.00 %',
+      '  - Windows 10, -2.401 %, , 0.8, S, 49.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
+      '  - Windows 10, -, , 0.8, NS, 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, -, 99.00 %',
+      '  - Windows 10, -2.401 %, , 1.2, S, 49.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
+      '  - Windows 10, -, , 1.2, NS, 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, -, 98.00 %',
+      '  - Windows 10, -2.401 %, , 2, S, 48.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %',
+      '  - Windows 10, -, , 2, NS, 98.00 %',
     ]);
     // 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, -, , -, -, 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 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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 %',
+      '  - Windows 10, -, , 0.8, NS, 99.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
+      '  - Windows 10, -2.401 %, , 0.8, S, 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 %',
+      '  - Windows 10, -, , 1.2, NS, 99.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
+      '  - Windows 10, -2.401 %, , 1.2, S, 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 %',
+      '  - Windows 10, -, , 2, NS, 98.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
+      '  - Windows 10, -2.401 %, , 2, S, 48.00 %',
     ]);
     // 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, 1.078 %, Improvement, 0.1, , 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
-      '  - Windows 10, -2.401 %, , -, , 50.00 %',
+      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 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 %',
+      '  - Windows 10, -, , 0.8, NS, 99.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
+      '  - Windows 10, -2.401 %, , 0.8, S, 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 %',
+      '  - Windows 10, -, , 1.2, NS, 99.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
+      '  - Windows 10, -2.401 %, , 1.2, S, 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 %',
+      '  - Windows 10, -, , 2, NS, 98.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
+      '  - Windows 10, -2.401 %, , 2, S, 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, -2.401 %, , -, , 50.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, , 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, , 25.00 %',
-      '  - Windows 10, -, , -, -, 100.00 %',
+      '  - Windows 10, -2.401 %, , -, S, 50.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Windows 10, -, , -, NS, 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, -, 99.00 %',
+      '  - Windows 10, -2.401 %, , 0.8, S, 49.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
+      '  - Windows 10, -, , 0.8, NS, 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, -, 99.00 %',
+      '  - Windows 10, -2.401 %, , 1.2, S, 49.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
+      '  - Windows 10, -, , 1.2, NS, 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, -, 98.00 %',
+      '  - Windows 10, -2.401 %, , 2, S, 48.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %',
+      '  - Windows 10, -, , 2, NS, 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 212640cdb..203ed4340 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: 0.963 %, -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: 0.963 %, -0.04, NS, 15.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 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: 1.135 %, 0.12, NS, 25.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'browser.html: 0.963 %, -0.04, NS, 15.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 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: 0.98 %, 0.01, NS, 45.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'browser.html: 0.963 %, -0.04, NS, 15.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'regression.html: 1.135 %, 0.12, NS, 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([
-        '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: 0.963 %, -0.04, -, 15.00%',
-        'tablemutation.html: 0.98 %, 0.01, -, 45.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'browser.html: 0.963 %, -0.04, NS, 15.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
       ]);
       // 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([
-        '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: 0.963 %, -0.04, -, 15.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'browser.html: 0.963 %, -0.04, NS, 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: 0.963 %, -0.04, NS, 15.00%',
+        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 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: 0.963 %, -0.05, NS, 50.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'browser.html: 0.963 %, -0.04, NS, 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: 0.98 %, 0.01, NS, 45.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'browser.html: 0.963 %, -0.04, NS, 15.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'regression.html: 1.135 %, 0.12, NS, 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: 1.135 %, 0.12, NS, 25.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'browser.html: 0.963 %, -0.04, NS, 15.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 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: 1.135 %, 0.12, NS, 25.00%',
+        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'browser.html: 0.963 %, -0.04, NS, 15.00%',
+        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'tablemutation.html: 0.98 %, 0.01, NS, 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 adfbf5770..def10e054 100644
--- a/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
@@ -194,11 +194,11 @@ describe('SubtestsRevisionRow Component', () => {
     expect(effects).toHaveTextContent('60.00%');
 
     // The fixture runs don't yield a CI that excludes 0 once precomputed by
-    // the loader, so this row renders the "-" placeholder. This test mounts
-    // the row directly without the loader, leaving bootstrapCi undefined,
-    // which also falls back to "-". Either way: no icon is rendered.
+    // the loader, so this row renders "NS". This test mounts the row directly
+    // without the loader, leaving bootstrapCi undefined, which also falls
+    // back to "NS".
     const significanceCell = roles[8];
-    expect(significanceCell).toHaveTextContent('-');
+    expect(significanceCell).toHaveTextContent('NS');
 
     const cliffs_delta = roles[6]?.childNodes[1];
     expect(cliffs_delta).toHaveTextContent('0.02');
diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index 78d7450be..c59fe72da 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -824,20 +824,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -1036,20 +1023,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -1248,20 +1222,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -1460,20 +1421,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index 3d6fe6413..417d4b159 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1797,20 +1797,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -2009,20 +1996,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -2221,20 +2195,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -2520,20 +2481,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -4745,20 +4693,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -4970,20 +4905,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -5182,20 +5104,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              <svg
-                                aria-hidden="true"
-                                class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                                data-testid="KeyboardDoubleArrowUpIcon"
-                                focusable="false"
-                                viewBox="0 0 24 24"
-                              >
-                                <path
-                                  d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                                />
-                                <path
-                                  d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                                />
-                              </svg>
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -5477,7 +5386,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              -
+                              NS
                             </div>
                             <div
                               class="total-runs cell"
@@ -5900,26 +5809,26 @@ 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 %",
-  "  - Windows 10, -, , -, -, 100.00 %",
-  "  - Windows 10, -2.401 %, , -, , 50.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %",
+  "  - Windows 10, -, , -, NS, 100.00 %",
+  "  - Windows 10, -2.401 %, , -, S, 50.00 %",
   "  rev: tictactoe",
-  "  - Linux 18.04, 1.849 %, Regression, 0.8, , 44.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 0.9, , 24.00 %",
-  "  - Windows 10, -, , 0.8, -, 99.00 %",
-  "  - Windows 10, -2.401 %, , 0.8, , 49.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %",
+  "  - Windows 10, -, , 0.8, NS, 99.00 %",
+  "  - Windows 10, -2.401 %, , 0.8, S, 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 %",
-  "  - Windows 10, -, , 1.2, -, 99.00 %",
-  "  - Windows 10, -2.401 %, , 1.2, , 49.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %",
+  "  - Windows 10, -, , 1.2, NS, 99.00 %",
+  "  - Windows 10, -2.401 %, , 1.2, S, 49.00 %",
   "  rev: tictactoe",
-  "  - Linux 18.04, 1.849 %, Regression, 2, , 43.00 %",
-  "  - macOS 10.15, 1.078 %, Improvement, 2.1, , 23.00 %",
-  "  - Windows 10, -, , 2, -, 98.00 %",
-  "  - Windows 10, -2.401 %, , 2, , 48.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %",
+  "  - Windows 10, -, , 2, NS, 98.00 %",
+  "  - Windows 10, -2.401 %, , 2, S, 48.00 %",
 ]
 `;
 
@@ -5972,26 +5881,26 @@ 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 %",
-  "  - 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 %, , -, S, 50.00 %",
+  "  - Windows 10, -, , -, NS, 100.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %",
   "  rev: tictactoe",
-  "  - Windows 10, -2.401 %, , 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 %",
+  "  - Windows 10, -2.401 %, , 0.8, S, 49.00 %",
+  "  - Windows 10, -, , 0.8, NS, 99.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %",
   "a11yr aria.html opt e10s fission stylo webrender",
   "  rev: spam",
-  "  - Windows 10, -2.401 %, , 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 %",
+  "  - Windows 10, -2.401 %, , 1.2, S, 49.00 %",
+  "  - Windows 10, -, , 1.2, NS, 99.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %",
   "  rev: tictactoe",
-  "  - Windows 10, -2.401 %, , 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 %",
+  "  - Windows 10, -2.401 %, , 2, S, 48.00 %",
+  "  - Windows 10, -, , 2, NS, 98.00 %",
+  "  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %",
+  "  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %",
 ]
 `;
 
@@ -6296,20 +6205,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="significance cell"
         role="cell"
       >
-        <svg
-          aria-hidden="true"
-          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-          data-testid="KeyboardDoubleArrowUpIcon"
-          focusable="false"
-          viewBox="0 0 24 24"
-        >
-          <path
-            d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-          />
-          <path
-            d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-          />
-        </svg>
+        S
       </div>
       <div
         class="total-runs cell"
@@ -6560,20 +6456,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="significance cell"
         role="cell"
       >
-        <svg
-          aria-hidden="true"
-          class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-          data-testid="KeyboardDoubleArrowUpIcon"
-          focusable="false"
-          viewBox="0 0 24 24"
-        >
-          <path
-            d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-          />
-          <path
-            d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-          />
-        </svg>
+        S
       </div>
       <div
         class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index 15b655c1f..fc78a9569 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -1953,20 +1953,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -2165,20 +2152,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -2377,20 +2351,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -2589,20 +2550,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  <svg
-                    aria-hidden="true"
-                    class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-54rgmy-MuiSvgIcon-root"
-                    data-testid="KeyboardDoubleArrowUpIcon"
-                    focusable="false"
-                    viewBox="0 0 24 24"
-                  >
-                    <path
-                      d="M6 17.59 7.41 19 12 14.42 16.59 19 18 17.59l-6-6z"
-                    />
-                    <path
-                      d="m6 11 1.41 1.41L12 7.83l4.59 4.58L18 11l-6-6z"
-                    />
-                  </svg>
+                  S
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index f5c28e517..36fdf7823 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -1191,7 +1191,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -1339,7 +1339,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -1487,7 +1487,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -1635,7 +1635,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -1783,7 +1783,7 @@ exports[`SubtestsResultsView Component Tests should render the subtests results
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -3104,7 +3104,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -3267,7 +3267,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -3417,7 +3417,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -3567,7 +3567,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -3730,7 +3730,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -4667,7 +4667,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -4830,7 +4830,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -4980,7 +4980,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -5130,7 +5130,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -5293,7 +5293,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -6230,7 +6230,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -6393,7 +6393,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -6543,7 +6543,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -6693,7 +6693,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -6856,7 +6856,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -7791,7 +7791,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -7939,7 +7939,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -8087,7 +8087,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -8235,7 +8235,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -8383,7 +8383,7 @@ exports[`SubtestsViewCompareOverTime Component Tests should render the subtests
                   class="significance cell"
                   role="cell"
                 >
-                  -
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/common/constants.ts b/src/common/constants.ts
index dfb4aea28..53af99230 100644
--- a/src/common/constants.ts
+++ b/src/common/constants.ts
@@ -324,7 +324,7 @@ export const MANN_WHITNEY_U = 'mann-whitney-u' as TestVersion;
 export const STUDENT_T = 'student-t' as TestVersion;
 
 export const tooltipSignificance =
-  'Significance of the comparison as determined by a 95% bootstrap (BCa) confidence interval on the difference of medians. A comparison is significant when the interval excludes zero.';
+  'Significance of the comparison as determined by a 95% bootstrap (BCa) confidence interval on the difference of medians. "S" (Significant) means the interval excludes zero — the medians differ. "NS" (Not Significant) means the interval includes zero — no detectable difference.';
 export const tooltipStatusMannWhitney =
   'An improvement or regression being shown here means that the effect size is meaningful and the difference is statistically significant.';
 export const tooltipTotalRuns =
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index a2eb9ead7..330203ee8 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -1,4 +1,3 @@
-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';
@@ -245,12 +244,12 @@ export const mannWhitneyStrategy = {
           {
             label: 'Significant',
             key: 'significant',
-            icon: <KeyboardDoubleArrowUpIcon fontSize='small' />,
+            icon: <div>S</div>,
           },
           {
             label: 'Not Significant',
             key: 'not significant',
-            icon: <div>-</div>,
+            icon: <div>NS</div>,
           },
         ],
         matchesFunction(result: MannWhitneyResultsItem, valueKey: string) {
@@ -396,11 +395,7 @@ export const mannWhitneyStrategy = {
           {clesVal ? `${clesVal}% ` : '-'}
         </div>
         <div className='significance cell' role='cell'>
-          {bootstrapCi?.significant ? (
-            <KeyboardDoubleArrowUpIcon fontSize='small' />
-          ) : (
-            '-'
-          )}
+          {bootstrapCi?.significant ? 'S' : 'NS'}
         </div>
       </>
     );
@@ -584,11 +579,7 @@ export const mannWhitneyStrategy = {
           {clesValue}
         </div>
         <div className='significance cell' role='cell'>
-          {bootstrapCi?.significant ? (
-            <KeyboardDoubleArrowUpIcon fontSize='small' />
-          ) : (
-            '-'
-          )}
+          {bootstrapCi?.significant ? 'S' : 'NS'}
         </div>
       </>
     );

From 1f4ca56725c8ba9359d635b40c4f10d3931d686d Mon Sep 17 00:00:00 2001
From: Carla Severe <csevere@mozilla.com>
Date: Wed, 24 Jun 2026 18:05:04 -0700
Subject: [PATCH 3/3] mannWhitney: precompute bootstrap CI on replicates when
 available

mannWhitney: lazy-precompute Sig CI to restore production-level load speed
---
 .../CompareResults/ResultsTable.test.tsx      | 138 ++++++-------
 .../SubtestsResultsView.test.tsx              |  36 ++--
 .../SubtestsRevisionRow.test.tsx              |  11 +-
 .../OverTimeResultsView.test.tsx.snap         |   8 +-
 .../__snapshots__/ResultsTable.test.tsx.snap  |  18 +-
 .../__snapshots__/ResultsView.test.tsx.snap   |  22 +--
 .../SubtestsResultsView.test.tsx.snap         |  18 +-
 src/common/testVersions/mannWhitney.tsx       | 181 ++++++++++++++----
 src/components/CompareResults/loader.ts       |  29 +--
 .../CompareResults/overTimeLoader.ts          |  16 +-
 .../CompareResults/subtestsLoader.ts          |  16 +-
 .../CompareResults/subtestsOverTimeLoader.tsx |  14 +-
 12 files changed, 286 insertions(+), 221 deletions(-)

diff --git a/src/__tests__/CompareResults/ResultsTable.test.tsx b/src/__tests__/CompareResults/ResultsTable.test.tsx
index 9e8d4f7d4..9f6921cbf 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, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
       '  rev: devilrabbit',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
     ]);
     expect(screen.getByRole('rowgroup')).toMatchSnapshot();
   });
@@ -748,11 +748,11 @@ 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, S, 25.00 %',
-      '  - inexistant, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - inexistant, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
     ]);
 
@@ -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, S, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'linux', 'android', 'ios'],
@@ -775,11 +775,11 @@ 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, S, 25.00 %',
-      '  - inexistant, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - inexistant, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 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, S, 25.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 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, S, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['osx', 'android', 'ios', 'linux'],
@@ -809,11 +809,11 @@ 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, S, 25.00 %',
-      '  - inexistant, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - inexistant, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
@@ -821,9 +821,9 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     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, S, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
@@ -833,8 +833,8 @@ 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, -, S, 45.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
@@ -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, S, 25.00 %',
+      '  - Android, 1.078 %, Improvement, 0.1, NS, 25.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       platform: ['android'],
@@ -883,9 +883,9 @@ 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, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 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, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 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, -, S, 45.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
       status: ['regression'],
@@ -914,8 +914,8 @@ 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, S, 25.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({
@@ -925,9 +925,9 @@ 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',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
     ]);
     expect(summarizeTableFiltersFromUrl()).toEqual({});
@@ -935,7 +935,7 @@ describe('Results Table for MannWhitneyResultsItem for mann-whitney-u testVersio
     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, -, S, 45.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 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, S, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 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, S, 25.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
     ]);
     const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
     expect(await summarizeTableFiltersFromCheckboxes(user)).toEqual({
@@ -997,25 +997,25 @@ 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: spam',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
-      '  - Windows 10, -, , 1.2, NS, 99.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, NS, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, NS, 24.00 %',
+      '  - Windows 10, -, , 1.2, S, 99.00 %',
       '  - Windows 10, -2.401 %, , 1.2, S, 49.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 2.1, S, 23.00 %',
-      '  - Windows 10, -, , 2, NS, 98.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, NS, 43.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, NS, 23.00 %',
+      '  - Windows 10, -, , 2, S, 98.00 %',
       '  - Windows 10, -2.401 %, , 2, S, 48.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: spam',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
       '  rev: tictactoe',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
-      '  - Windows 10, -, , 0.8, NS, 99.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, NS, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, NS, 24.00 %',
+      '  - Windows 10, -, , 0.8, S, 99.00 %',
       '  - Windows 10, -2.401 %, , 0.8, S, 49.00 %',
     ]);
     // It should have the "descending" SVG.
@@ -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, 1.078 %, Improvement, 2.1, S, 23.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 2, S, 43.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 2.1, NS, 23.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 2, NS, 43.00 %',
       '  - Windows 10, -2.401 %, , 2, S, 48.00 %',
-      '  - Windows 10, -, , 2, NS, 98.00 %',
+      '  - Windows 10, -, , 2, S, 98.00 %',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 1.3, S, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 1.2, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 1.3, NS, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 1.2, NS, 44.00 %',
       '  - Windows 10, -2.401 %, , 1.2, S, 49.00 %',
-      '  - Windows 10, -, , 1.2, NS, 99.00 %',
+      '  - Windows 10, -, , 1.2, S, 99.00 %',
       'a11yr dhtml.html opt e10s fission stylo webrender',
       '  rev: tictactoe',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.9, S, 24.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, 0.8, S, 44.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.9, NS, 24.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, 0.8, NS, 44.00 %',
       '  - Windows 10, -2.401 %, , 0.8, S, 49.00 %',
-      '  - Windows 10, -, , 0.8, NS, 99.00 %',
+      '  - Windows 10, -, , 0.8, S, 99.00 %',
       '  rev: spam',
-      '  - macOS 10.15, 1.078 %, Improvement, 0.1, S, 25.00 %',
-      '  - Linux 18.04, 1.849 %, Regression, -, S, 45.00 %',
+      '  - macOS 10.15, 1.078 %, Improvement, 0.1, NS, 25.00 %',
+      '  - Linux 18.04, 1.849 %, Regression, -, NS, 45.00 %',
       '  - Windows 10, -2.401 %, , -, S, 50.00 %',
-      '  - Windows 10, -, , -, NS, 100.00 %',
+      '  - Windows 10, -, , -, S, 100.00 %',
     ]);
     // It should have the "ascending" SVG.
     expect(deltaButton).toMatchSnapshot();
diff --git a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
index 203ed4340..1a86b53f1 100644
--- a/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsResultsView.test.tsx
@@ -528,9 +528,9 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       // Initial view (alphabetical ordered, even if "sort by subtests" isn't specified
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
         'browser.html: 0.963 %, -0.04, NS, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
-        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
-        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'dhtml.html: 1.135 %, 0.02, S, 60.00%',
+        'improvement.html: 0.963 %, -0.05, S, 50.00%',
+        'regression.html: 1.135 %, 0.12, S, 25.00%',
         'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
       ]);
 
@@ -542,10 +542,10 @@ 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, NS, 25.00%',
-        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'regression.html: 1.135 %, 0.12, S, 25.00%',
+        'improvement.html: 0.963 %, -0.05, S, 50.00%',
         'browser.html: 0.963 %, -0.04, NS, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'dhtml.html: 1.135 %, 0.02, S, 60.00%',
         'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
       ]);
 
@@ -558,10 +558,10 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await user.click(deltaButton);
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
         'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
-        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'dhtml.html: 1.135 %, 0.02, S, 60.00%',
         'browser.html: 0.963 %, -0.04, NS, 15.00%',
-        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
-        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'improvement.html: 0.963 %, -0.05, S, 50.00%',
+        'regression.html: 1.135 %, 0.12, S, 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(deltaButton).toMatchSnapshot();
@@ -633,10 +633,10 @@ describe('SubtestsResultsView Component Tests for mann-whitney-u testVersion', (
       await screen.findByText('dhtml.html');
       expect(summarizeVisibleRows('mann-whitney-u')).toEqual([
         'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
-        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'dhtml.html: 1.135 %, 0.02, S, 60.00%',
         'browser.html: 0.963 %, -0.04, NS, 15.00%',
-        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
-        'regression.html: 1.135 %, 0.12, NS, 25.00%',
+        'improvement.html: 0.963 %, -0.05, S, 50.00%',
+        'regression.html: 1.135 %, 0.12, S, 25.00%',
       ]);
       // It should have the "ascending" SVG.
       expect(screen.getByRole('button', { name: /CD/ })).toMatchSnapshot();
@@ -646,10 +646,10 @@ 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, NS, 25.00%',
-        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'regression.html: 1.135 %, 0.12, S, 25.00%',
+        'improvement.html: 0.963 %, -0.05, S, 50.00%',
         'browser.html: 0.963 %, -0.04, NS, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'dhtml.html: 1.135 %, 0.02, S, 60.00%',
         'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
       ]);
       // It should have the "descending" SVG.
@@ -659,10 +659,10 @@ 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, NS, 25.00%',
-        'improvement.html: 0.963 %, -0.05, NS, 50.00%',
+        'regression.html: 1.135 %, 0.12, S, 25.00%',
+        'improvement.html: 0.963 %, -0.05, S, 50.00%',
         'browser.html: 0.963 %, -0.04, NS, 15.00%',
-        'dhtml.html: 1.135 %, 0.02, NS, 60.00%',
+        'dhtml.html: 1.135 %, 0.02, S, 60.00%',
         'tablemutation.html: 0.98 %, 0.01, NS, 45.00%',
       ]);
       // It should have the "descending" SVG.
diff --git a/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx b/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
index def10e054..25ce9e6f7 100644
--- a/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
+++ b/src/__tests__/CompareResults/SubtestsRevisionRow.test.tsx
@@ -193,12 +193,13 @@ describe('SubtestsRevisionRow Component', () => {
     const effects = roles[7]?.childNodes[0];
     expect(effects).toHaveTextContent('60.00%');
 
-    // The fixture runs don't yield a CI that excludes 0 once precomputed by
-    // the loader, so this row renders "NS". This test mounts the row directly
-    // without the loader, leaving bootstrapCi undefined, which also falls
-    // back to "NS".
+    // The Sig cell renders lazily: when no CI has been cached on the row
+    // yet, it falls back to `mann_whitney_test.interpretation` from the
+    // backend. The fixture's interpretation is "significant", so the cell
+    // shows "S" here. First click on the Sig column header would trigger
+    // BCa and could flip this if the CI includes zero.
     const significanceCell = roles[8];
-    expect(significanceCell).toHaveTextContent('NS');
+    expect(significanceCell).toHaveTextContent('S');
 
     const cliffs_delta = roles[6]?.childNodes[1];
     expect(cliffs_delta).toHaveTextContent('0.02');
diff --git a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
index c59fe72da..3adc84d11 100644
--- a/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/OverTimeResultsView.test.tsx.snap
@@ -824,7 +824,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -1023,7 +1023,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -1222,7 +1222,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -1421,7 +1421,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
index 417d4b159..873f01de2 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsTable.test.tsx.snap
@@ -1797,7 +1797,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              S
+                              NS
                             </div>
                             <div
                               class="total-runs cell"
@@ -1996,7 +1996,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              S
+                              NS
                             </div>
                             <div
                               class="total-runs cell"
@@ -2195,7 +2195,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              S
+                              NS
                             </div>
                             <div
                               class="total-runs cell"
@@ -2481,7 +2481,7 @@ exports[`Results Table Should match snapshot 1`] = `
                               class="significance cell"
                               role="cell"
                             >
-                              S
+                              NS
                             </div>
                             <div
                               class="total-runs cell"
@@ -4693,7 +4693,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              S
+                              NS
                             </div>
                             <div
                               class="total-runs cell"
@@ -4905,7 +4905,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              S
+                              NS
                             </div>
                             <div
                               class="total-runs cell"
@@ -5386,7 +5386,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
                               class="significance cell"
                               role="cell"
                             >
-                              NS
+                              S
                             </div>
                             <div
                               class="total-runs cell"
@@ -6205,7 +6205,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="significance cell"
         role="cell"
       >
-        S
+        NS
       </div>
       <div
         class="total-runs cell"
@@ -6456,7 +6456,7 @@ exports[`Results Table for MannWhitneyResultsItem for mann-whitney-u testVersion
         class="significance cell"
         role="cell"
       >
-        S
+        NS
       </div>
       <div
         class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
index fc78a9569..43c700f88 100644
--- a/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/ResultsView.test.tsx.snap
@@ -277,15 +277,15 @@ exports[`Results View Should display Base, New and Common graphs with replicates
                   Δ median
                 </strong>
                  = 
-                +9.00
+                +8.74
                  
                 ms
                  (+1.5%)
                  
                 95% CI [
-                +0.00
+                +3.57
                 , 
-                +18.01
+                +18.16
                 ]
               </span>
             </div>
@@ -319,12 +319,12 @@ exports[`Results View Should display Base, New and Common graphs with replicates
                 </strong>
                 : We are 95% confident the median difference is between 
                 <strong>
-                  +0.00
+                  +3.57
                 </strong>
                  and
                  
                 <strong>
-                  +18.01
+                  +18.16
                 </strong>
               </span>
             </div>
@@ -815,7 +815,7 @@ exports[`Results View Should display Base, New and Common graphs with tooltips 1
                  (+1.5%)
                  
                 95% CI [
-                +3.27
+                +3.57
                 , 
                 +18.16
                 ]
@@ -851,7 +851,7 @@ exports[`Results View Should display Base, New and Common graphs with tooltips 1
                 </strong>
                 : We are 95% confident the median difference is between 
                 <strong>
-                  +3.27
+                  +3.57
                 </strong>
                  and
                  
@@ -1953,7 +1953,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -2152,7 +2152,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -2351,7 +2351,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
@@ -2550,7 +2550,7 @@ exports[`Results View The table should match snapshot and other elements should
                   class="significance cell"
                   role="cell"
                 >
-                  S
+                  NS
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
index 36fdf7823..77a18187b 100644
--- a/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
+++ b/src/__tests__/CompareResults/__snapshots__/SubtestsResultsView.test.tsx.snap
@@ -3267,7 +3267,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -3417,7 +3417,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -3567,7 +3567,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -4830,7 +4830,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -4980,7 +4980,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -5130,7 +5130,7 @@ exports[`SubtestsViewCompareOverTime Component Tests in mann-whitney-u testVersi
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -6393,7 +6393,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -6543,7 +6543,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
@@ -6693,7 +6693,7 @@ exports[`SubtestsViewCompareOverTime Component Tests renders over-time view when
                   class="significance cell"
                   role="cell"
                 >
-                  NS
+                  S
                 </div>
                 <div
                   class="total-runs cell"
diff --git a/src/common/testVersions/mannWhitney.tsx b/src/common/testVersions/mannWhitney.tsx
index 330203ee8..75b97346a 100644
--- a/src/common/testVersions/mannWhitney.tsx
+++ b/src/common/testVersions/mannWhitney.tsx
@@ -13,7 +13,10 @@ import {
   MannWhitneyResultsItem,
 } from '../../types/state';
 import { TableConfig } from '../../types/types';
-import { bootstrapMedianDiffCI } from '../../utils/bootstrap-ci';
+import {
+  bootstrapMedianDiffCI,
+  type BootstrapCI,
+} from '../../utils/bootstrap-ci';
 import { adaptUnit, formatNumber } from '../../utils/format';
 import { capitalize } from '../../utils/helpers';
 import { getBrowserDisplay, getPlatformShortName } from '../../utils/platform';
@@ -101,27 +104,103 @@ export function isDistributionNormal(result: MannWhitneyResultsItem): boolean {
   return checkDistributionNormality(result) !== 'neither';
 }
 
+// Cap on the per-side sample count fed into BCa. Replicates arrays can
+// run 300–600 values; BCa cost is roughly proportional to sample size, so
+// uncapped it dominates page load on tables with many rows. CI quality is
+// dominated by iteration count above ~50–100 samples — capping here keeps
+// the interval statistically equivalent while bounding cost.
+const BOOTSTRAP_SAMPLE_CAP = 100;
+// Fewer iterations than bootstrap-ci.ts's 9999 default. 1999 is still
+// well above the textbook BCa minimum (~1000) and ~5× cheaper.
+const BOOTSTRAP_ITERATIONS = 1999;
+
+// Stride-based subsample: pick `cap` evenly-spaced values from a larger
+// array. Deterministic (no RNG), preserves the full distribution shape,
+// and is O(cap) regardless of input length.
+function downsampleForBootstrap(values: number[]): number[] {
+  if (values.length <= BOOTSTRAP_SAMPLE_CAP) return values;
+  const out: number[] = new Array<number>(BOOTSTRAP_SAMPLE_CAP);
+  const stride = values.length / BOOTSTRAP_SAMPLE_CAP;
+  for (let i = 0; i < BOOTSTRAP_SAMPLE_CAP; i++) {
+    out[i] = values[Math.floor(i * stride)];
+  }
+  return out;
+}
+
+// Resolve a row's KDE/BCa input sample set: prefer replicates over the
+// aggregated runs. Mirrors RevisionRowExpandable's selection for the chart
+// and KdeModesPanel so every view of the row uses the same underlying data.
+// Returned arrays are NOT downsampled — callers feeding BCa should pass
+// them through `downsampleForBootstrap` first.
+function runsFor(result: MannWhitneyResultsItem): {
+  baseRuns: number[];
+  newRuns: number[];
+} {
+  const baseRuns =
+    result.base_runs_replicates && result.base_runs_replicates.length
+      ? result.base_runs_replicates
+      : (result.base_runs ?? []);
+  const newRuns =
+    result.new_runs_replicates && result.new_runs_replicates.length
+      ? result.new_runs_replicates
+      : (result.new_runs ?? []);
+  return { baseRuns, newRuns };
+}
+
 /**
- * Precompute the bootstrap (BCa)[see src/utils/bootstrap-ci.ts#L163-L203] CI for the difference of medians on every
- * Mann-Whitney result and attach it to `result.bootstrapCi`. Called from the
- * data loaders so the Sig column's filter/sort and the expanded-row alert can
- * read a precomputed value instead of triggering bootstrapMedianDiffCI per
- * row per render (BCa is ~10–30 ms/row and would tank sort interactions).
+ * Lazily compute (and cache) the bootstrap (BCa) [see
+ * src/utils/bootstrap-ci.ts#L163-L203] CI for the difference of medians
+ * on a single row.
+ *
+ * The lazy strategy: at load time we do NO BCa work (matches production
+ * speed). The Sig column's `matchesFunction`/`sortFunction`/cell-render
+ * call this helper as needed. Result is cached on `result.bootstrapCi`
+ * so the second click on the column is free.
+ *
+ * `undefined` vs `null`:
+ *   - `undefined` ⇒ never computed
+ *   - `null`      ⇒ computed but couldn't produce a CI (< 2 samples)
+ * We check `=== undefined` instead of `?? null` to keep that distinction.
  *
- * Rows without enough data (< 2 samples on either side) get `bootstrapCi:
- * null`; the column code treats that as "not significant".
+ * Uses the replicates-preferred sample selection (via `runsFor`) and the
+ * downsampled-for-BCa cap so per-row cost stays bounded regardless of how
+ * many replicates the backend ships. See `BOOTSTRAP_SAMPLE_CAP` and
+ * `BOOTSTRAP_ITERATIONS` above.
  */
-export function precomputeMannWhitneyCI(
-  results: MannWhitneyResultsItem[],
-): void {
-  for (const result of results) {
-    const baseRuns = result.base_runs ?? [];
-    const newRuns = result.new_runs ?? [];
-    result.bootstrapCi =
-      baseRuns.length >= 2 && newRuns.length >= 2
-        ? bootstrapMedianDiffCI(baseRuns, newRuns)
-        : null;
+export function getBootstrapCi(
+  result: MannWhitneyResultsItem,
+): BootstrapCI | null {
+  if (result.bootstrapCi !== undefined) return result.bootstrapCi;
+  const { baseRuns, newRuns } = runsFor(result);
+  const baseSamples = downsampleForBootstrap(baseRuns);
+  const newSamples = downsampleForBootstrap(newRuns);
+  const ci =
+    baseSamples.length >= 2 && newSamples.length >= 2
+      ? bootstrapMedianDiffCI(baseSamples, newSamples, BOOTSTRAP_ITERATIONS)
+      : null;
+  result.bootstrapCi = ci;
+  return ci;
+}
+
+// Decide whether the Sig cell should render "S" or "NS".
+//
+// Cell renders run for EVERY row on every render — we can't afford to
+// compute BCa here at load time. So the cell uses whichever signal is
+// available without forcing compute:
+//   - If the CI has been cached (filter/sort has been used, or the
+//     expanded-row alert ran), use it — keeps the column consistent with
+//     the rest of the UI on rows the user has engaged with.
+//   - Otherwise fall back to the backend's `mann_whitney_test.interpretation`
+//     — close to production's pre-branch behavior and free to read.
+//
+// First filter/sort click populates `bootstrapCi` for all rows; from then
+// on the column reads the CI-based verdict everywhere. So you only see the
+// fallback on first render before any Sig interaction.
+function isSignificantForDisplay(result: MannWhitneyResultsItem): boolean {
+  if (result.bootstrapCi !== undefined) {
+    return result.bootstrapCi?.significant ?? false;
   }
+  return result.mann_whitney_test?.interpretation === 'significant';
 }
 
 export const mannWhitneyStrategy = {
@@ -253,10 +332,11 @@ export const mannWhitneyStrategy = {
           },
         ],
         matchesFunction(result: MannWhitneyResultsItem, valueKey: string) {
-          // Significance comes from the precomputed bootstrap CI (see
-          // precomputeMannWhitneyCI above).
-          // Missing CI ⇒ treat as not-significant.
-          const isSig = result.bootstrapCi?.significant ?? false;
+          // Lazily compute and cache the CI on first filter-click. After
+          // that, the CI is read straight from `result.bootstrapCi` on
+          // every subsequent comparison/render (see getBootstrapCi above).
+          const ci = getBootstrapCi(result);
+          const isSig = ci?.significant ?? false;
           return (isSig ? 'significant' : 'not significant') === valueKey;
         },
         sortFunction(
@@ -267,11 +347,18 @@ export const mannWhitneyStrategy = {
           // this produces "significant first, then |medianDiff| desc"; in ASC
           // mode the inverse. Significance is the primary key, magnitude the
           // tie-breaker so the biggest changes float to the top of each group.
-          const sigA = resultA.bootstrapCi?.significant ?? false;
-          const sigB = resultB.bootstrapCi?.significant ?? false;
+          //
+          // First sort-click pays the BCa cost across all rows (the
+          // comparator is invoked O(n log n) times but each row is computed
+          // only once and cached via getBootstrapCi). Subsequent sorts are
+          // free.
+          const ciA = getBootstrapCi(resultA);
+          const ciB = getBootstrapCi(resultB);
+          const sigA = ciA?.significant ?? false;
+          const sigB = ciB?.significant ?? false;
           if (sigA !== sigB) return sigA ? 1 : -1;
-          const magA = Math.abs(resultA.bootstrapCi?.medianDiff ?? 0);
-          const magB = Math.abs(resultB.bootstrapCi?.medianDiff ?? 0);
+          const magA = Math.abs(ciA?.medianDiff ?? 0);
+          const magB = Math.abs(ciB?.medianDiff ?? 0);
           return magA - magB;
         },
       },
@@ -296,17 +383,22 @@ export const mannWhitneyStrategy = {
   },
 
   renderSubtestColumns(result: CombinedResultsItemType, expanded: boolean) {
+    const mwResult = result as MannWhitneyResultsItem;
     const {
       test,
       cliffs_delta,
       cles,
       direction_of_change,
-      bootstrapCi,
       base_measurement_unit: baseUnit,
       new_measurement_unit: newUnit,
       base_app: baseApp,
       new_app: newApp,
-    } = result as MannWhitneyResultsItem;
+    } = mwResult;
+    // See `isSignificantForDisplay` above — uses the cached CI when one
+    // exists and falls back to the backend interpretation otherwise.
+    // Computing BCa here on every cell render would re-introduce the
+    // per-row load cost we just removed.
+    const sigDisplay = isSignificantForDisplay(mwResult) ? 'S' : 'NS';
     const clesVal = ((cles?.cles ?? 0) * 100).toFixed(2);
     const baseAvgValue =
       (result as MannWhitneyResultsItem).base_standard_stats?.mean ?? 0;
@@ -395,7 +487,7 @@ export const mannWhitneyStrategy = {
           {clesVal ? `${clesVal}% ` : '-'}
         </div>
         <div className='significance cell' role='cell'>
-          {bootstrapCi?.significant ? 'S' : 'NS'}
+          {sigDisplay}
         </div>
       </>
     );
@@ -435,15 +527,18 @@ export const mannWhitneyStrategy = {
     // Prefer the precomputed CI populated by the loader. Fall back to an
     // inline compute for backwards compatibility (e.g. tests that mount the
     // strategy without going through a loader, or stale results without the
-    // field).
-    const baseRuns = mwResult.base_runs ?? [];
-    const newRuns = mwResult.new_runs ?? [];
-    const ci =
-      mwResult.bootstrapCi !== undefined
-        ? mwResult.bootstrapCi
-        : baseRuns.length > 0 && newRuns.length > 0
-          ? bootstrapMedianDiffCI(baseRuns, newRuns)
-          : null;
+    // field). `baseRuns`/`newRuns` is the full replicates-preferred set
+    // (used for the median below); the BCa fallback runs on the capped
+    // downsample so it can't hang on rich-replicates rows.
+    const { baseRuns, newRuns } = runsFor(mwResult);
+    const ci = (() => {
+      if (mwResult.bootstrapCi !== undefined) return mwResult.bootstrapCi;
+      const baseSamples = downsampleForBootstrap(baseRuns);
+      const newSamples = downsampleForBootstrap(newRuns);
+      return baseSamples.length >= 2 && newSamples.length >= 2
+        ? bootstrapMedianDiffCI(baseSamples, newSamples, BOOTSTRAP_ITERATIONS)
+        : null;
+    })();
     const rawUnit =
       mwResult.base_measurement_unit ?? mwResult.new_measurement_unit ?? 'ms';
     const { fmt, displayUnit } = ci
@@ -508,14 +603,18 @@ export const mannWhitneyStrategy = {
   },
 
   renderColumns(result: CombinedResultsItemType) {
+    const mwResult = result as MannWhitneyResultsItem;
     const {
       cliffs_delta,
       direction_of_change,
       cles,
-      bootstrapCi,
       base_standard_stats,
       new_standard_stats,
-    } = result as MannWhitneyResultsItem;
+    } = mwResult;
+    // See `isSignificantForDisplay` — uses the cached CI if a filter/sort
+    // populated it, otherwise the backend's interpretation. Cell renders
+    // can't afford to trigger BCa on every row at load time.
+    const sigDisplay = isSignificantForDisplay(mwResult) ? 'S' : 'NS';
     const clesValue = cles?.cles ? `${(cles.cles * 100).toFixed(2)} %` : '-';
     const baseMedian = base_standard_stats?.median ?? 0;
     const newMedian = new_standard_stats?.median ?? 0;
@@ -579,7 +678,7 @@ export const mannWhitneyStrategy = {
           {clesValue}
         </div>
         <div className='significance cell' role='cell'>
-          {bootstrapCi?.significant ? 'S' : 'NS'}
+          {sigDisplay}
         </div>
       </>
     );
diff --git a/src/components/CompareResults/loader.ts b/src/components/CompareResults/loader.ts
index 81fc998d1..10ad9e944 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 { precomputeMannWhitneyCI } 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';
@@ -199,13 +197,10 @@ 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 CI per row so the
-    // Sig column behaves the same way as it would on real backend data.
-    for (const oneRevsResults of results) {
-      precomputeMannWhitneyCI(
-        oneRevsResults as unknown as MannWhitneyResultsItem[],
-      );
-    }
+    // No bootstrap CI precompute here — the Sig column lazily computes (and
+    // caches) on the first filter/sort interaction via `getBootstrapCi` in
+    // mannWhitney.tsx. Eagerly precomputing on every row was blocking the
+    // table render at load time.
     // They're all based on the same rev
     const baseRev = results[0][0].base_rev;
     // And the same repository
@@ -301,19 +296,11 @@ export async function getComparisonInformation(
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((results) => {
-    // Precompute the bootstrap CI per row when the data is Mann-Whitney —
-    // the Sig column sorts/filters on it and the expanded-row alert reads it
-    // too, so doing the heavy BCa [see src/utils/bootstrap-ci.ts#L163-L203] work once here avoids per-render thrashing.
-    if (testVersion === MANN_WHITNEY_U) {
-      for (const oneRevsResults of results) {
-        precomputeMannWhitneyCI(
-          oneRevsResults as unknown as MannWhitneyResultsItem[],
-        );
-      }
-    }
-    return results;
   });
+  // No bootstrap CI precompute here — see the lazy `getBootstrapCi` helper
+  // in mannWhitney.tsx. Eager precompute on every row was blocking table
+  // render; lazy compute defers the BCa cost to the first Sig filter/sort
+  // click (and caches per row from then on).
 
   // TODO what happens if there's no result?
   const baseRevInfoPromise = memoizedFetchRevisionForRepository({
diff --git a/src/components/CompareResults/overTimeLoader.ts b/src/components/CompareResults/overTimeLoader.ts
index d4704c8b4..2aa012276 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 { precomputeMannWhitneyCI } 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';
@@ -230,18 +228,10 @@ export async function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((results) => {
-    // Same precompute as the main loader so the Sig column has a precomputed
-    // CI to sort/filter on without recomputing per render.
-    if (testVersion === MANN_WHITNEY_U) {
-      for (const oneRevsResults of results) {
-        precomputeMannWhitneyCI(
-          oneRevsResults as unknown as MannWhitneyResultsItem[],
-        );
-      }
-    }
-    return results;
   });
+  // No bootstrap CI precompute — the Sig column lazily computes (and caches)
+  // via `getBootstrapCi` in mannWhitney.tsx on the first filter/sort click.
+  // Same change as the main loader, applied here to keep load time aligned.
 
   const newRevsInfoPromises = newRevs.map((newRev, i) =>
     memoizedFetchRevisionForRepository({
diff --git a/src/components/CompareResults/subtestsLoader.ts b/src/components/CompareResults/subtestsLoader.ts
index bff1098ab..f1aa44412 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 { precomputeMannWhitneyCI } 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
@@ -187,17 +186,10 @@ export function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((subtestResults) => {
-    // Precompute the bootstrap CI for the Sig column when these are
-    // Mann-Whitney results. Subtests return a flat array (one entry per
-    // subtest), not the per-revision nesting the main loader has.
-    if (testVersion === MANN_WHITNEY_U) {
-      precomputeMannWhitneyCI(
-        subtestResults as unknown as MannWhitneyResultsItem[],
-      );
-    }
-    return subtestResults;
   });
+  // No bootstrap CI precompute — the Sig column lazily computes (and
+  // caches) on the first filter/sort interaction via `getBootstrapCi` in
+  // mannWhitney.tsx. Eager precompute was blocking table render at load.
 
   return {
     results,
diff --git a/src/components/CompareResults/subtestsOverTimeLoader.tsx b/src/components/CompareResults/subtestsOverTimeLoader.tsx
index a9edd4b9f..415ec7469 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 { precomputeMannWhitneyCI } 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 +212,11 @@ export function loader({ request }: { request: Request }) {
     replicates,
     testVersion,
     silvermanKDEEnabled,
-  }).then((subtestResults) => {
-    if (testVersion === MANN_WHITNEY_U) {
-      precomputeMannWhitneyCI(
-        subtestResults as unknown as MannWhitneyResultsItem[],
-      );
-    }
-    return subtestResults;
   });
+  // No bootstrap CI precompute — the Sig column lazily computes (and
+  // caches) via `getBootstrapCi` in mannWhitney.tsx on the first
+  // filter/sort click. Same change as the other loaders to keep load
+  // time aligned with production.
 
   return {
     results,