Calculate and report variance in performance results

test/performance/config/performance-reporter.ts

@@ -13,7 +13,7 @@ import type {
 /**
  * Internal dependencies
  */
-import { average, median, minimum, maximum, round } from '../utils';
+import { average, variance, round } from '../utils';
 
 export interface WPRawPerformanceResults {
 	timeToFirstByte: number[];
@@ -40,25 +40,45 @@ export interface WPRawPerformanceResults {
 
 export interface WPPerformanceResults {
 	timeToFirstByte?: number;
+	timeToFirstByteV?: number;
 	largestContentfulPaint?: number;
+	largestContentfulPaintV?: number;
 	lcpMinusTtfb?: number;
+	lcpMinusTtfbV?: number;
 	serverResponse?: number;
+	serverResponseV?: number;
 	firstPaint?: number;
+	firstPaintV?: number;
 	domContentLoaded?: number;
+	domContentLoadedV?: number;
 	loaded?: number;
+	loadedV?: number;
 	firstContentfulPaint?: number;
+	firstContentfulPaintV?: number;
 	firstBlock?: number;
+	firstBlockV?: number;
 	type?: number;
+	typeV?: number;
 	typeWithoutInspector?: number;
+	typeWithoutInspectorV?: number;
 	typeWithTopToolbar?: number;
+	typeWithTopToolbarV?: number;
 	typeContainer?: number;
+	typeContainerV?: number;
 	focus?: number;
+	focusV?: number;
 	inserterOpen?: number;
+	inserterOpenV?: number;
 	inserterSearch?: number;
+	inserterSearchV?: number;
 	inserterHover?: number;
+	inserterHoverV?: number;
 	loadPatterns?: number;
+	loadPatternsV?: number;
 	listViewOpen?: number;
+	listViewOpenV?: number;
 	navigate?: number;
+	navigateV?: number;
 }
 
 /**
@@ -72,26 +92,46 @@ export function curateResults(
 	results: WPRawPerformanceResults
 ): WPPerformanceResults {
 	const output = {
-		timeToFirstByte: median( results.timeToFirstByte ),
-		largestContentfulPaint: median( results.largestContentfulPaint ),
-		lcpMinusTtfb: median( results.lcpMinusTtfb ),
-		serverResponse: median( results.serverResponse ),
-		firstPaint: median( results.firstPaint ),
-		domContentLoaded: median( results.domContentLoaded ),
-		loaded: median( results.loaded ),
-		firstContentfulPaint: median( results.firstContentfulPaint ),
-		firstBlock: median( results.firstBlock ),
+		timeToFirstByte: average( results.timeToFirstByte ),
+		timeToFirstByteV: variance( results.timeToFirstByte ),
+		largestContentfulPaint: average( results.largestContentfulPaint ),
+		largestContentfulPaintV: variance( results.largestContentfulPaint ),
+		lcpMinusTtfb: average( results.lcpMinusTtfb ),
+		lcpMinusTtfbV: variance( results.lcpMinusTtfb ),
+		serverResponse: average( results.serverResponse ),
+		serverResponseV: variance( results.serverResponse ),
+		firstPaint: average( results.firstPaint ),
+		firstPaintV: variance( results.firstPaint ),
+		domContentLoaded: average( results.domContentLoaded ),
+		domContentLoadedV: variance( results.domContentLoaded ),
+		loaded: average( results.loaded ),
+		loadedV: variance( results.loaded ),
+		firstContentfulPaint: average( results.firstContentfulPaint ),
+		firstContentfulPaintV: variance( results.firstContentfulPaint ),
+		firstBlock: average( results.firstBlock ),
+		firstBlockV: variance( results.firstBlock ),
 		type: average( results.type ),
+		typeV: variance( results.type ),
 		typeWithoutInspector: average( results.typeWithoutInspector ),
+		typeWithoutInspectorV: variance( results.typeWithoutInspector ),
 		typeWithTopToolbar: average( results.typeWithTopToolbar ),
+		typeWithTopToolbarV: variance( results.typeWithTopToolbar ),
 		typeContainer: average( results.typeContainer ),
+		typeContainerV: variance( results.typeContainer ),
 		focus: average( results.focus ),
+		focusV: variance( results.focus ),
 		inserterOpen: average( results.inserterOpen ),
+		inserterOpenV: variance( results.inserterOpen ),
 		inserterSearch: average( results.inserterSearch ),
+		inserterSearchV: variance( results.inserterSearch ),
 		inserterHover: average( results.inserterHover ),
+		inserterHoverV: variance( results.inserterHover ),
 		loadPatterns: average( results.loadPatterns ),
+		loadPatternsV: variance( results.loadPatterns ),
 		listViewOpen: average( results.listViewOpen ),
-		navigate: median( results.navigate ),
+		listViewOpenV: variance( results.listViewOpen ),
+		navigate: average( results.navigate ),
+		navigateV: variance( results.navigate ),
 	};
 
 	return (

test/performance/utils.js

@@ -15,6 +15,15 @@ export function average( array ) {
 	return sum( array ) / array.length;
 }
 
+export function variance( array ) {
+	if ( ! array || ! array.length ) return undefined;
+
+	return Math.sqrt(
+		sum( array.map( ( x ) => x ** 2 ) ) / array.length -
+			( sum( array ) / array.length ) ** 2
+	);
+}
+
 export function median( array ) {
 	if ( ! array || ! array.length ) return undefined;