Remove variance

src/print/stats/prefix.js

@@ -31,5 +31,4 @@ const PLUS_MINUS = '±'
 const PREFIXES = {
   diff: getArrow,
   deviation: getPlusMinus,
-  variance: getPlusMinus,
 }

src/print/stats/skip.js

@@ -1,16 +1,15 @@
 // Statistics are now shown if:
 //  - undefined (e.g. `diff` with no previous benchmark)
-//  - deviation|variance if not enough samples
+//  - deviation if not enough samples
 export const shouldSkipStat = function({ stat, name, loops }) {
   return (
     stat === undefined ||
-    (DEVIATION_STATS.includes(name) && shouldSkipDeviation(stat, loops))
+    (name === 'deviation' && shouldSkipDeviation(stat, loops))
   )
 }
 
 const shouldSkipDeviation = function(stat, loops) {
   return stat === 0 || loops < MIN_LOOPS
 }
 
-const DEVIATION_STATS = ['deviation', 'variance']
 const MIN_LOOPS = 10

src/print/stats/types.js

@@ -8,7 +8,6 @@ export const STAT_TYPES = {
   diff: 'percentage',
   limit: 'scalar',
   deviation: 'percentage',
-  variance: 'scalar',
   count: 'count',
   loops: 'count',
   repeat: 'count',

src/report/reporters/debug/main.js

@@ -50,7 +50,6 @@ const STATS = [
   { name: 'diffPretty', shortName: 'dif' },
   { name: 'limitPretty', shortName: 'lmt' },
   { name: 'deviationPretty', shortName: 'dev' },
-  { name: 'variancePretty', shortName: 'vrc' },
   { name: 'countPretty', shortName: 'cnt' },
   { name: 'loopsPretty', shortName: 'lps' },
   { name: 'repeatPretty', shortName: 'rpt' },

src/stats/compute.js

@@ -1,6 +1,6 @@
 import { sortNumbers } from '../utils/sort.js'
 
-import { getMedian, getMean, getVariance, getDeviation } from './methods.js'
+import { getMedian, getMean, getDeviation } from './methods.js'
 import { getPercentiles } from './percentiles.js'
 import { getHistogram } from './histogram.js'
 
@@ -28,9 +28,9 @@ const reduceCount = function(totalCount, { count }) {
 // Perform the statistical logic.
 // Note that when `repeat > 1`, the distribution of the measured function will
 // be modified by the looping process and transformed to a bell shape, even if
-// if was not one. This means `percentiles`, `histogram`, `variance` and
-// `deviation` will have a different meaning: they visualize the measurements of
-// the function not function itself.
+// if was not one. This means `percentiles`, `histogram` and `deviation` will
+// have a different meaning: they visualize the measurements of the function not
+// function itself.
 // eslint-disable-next-line max-statements
 const computeStats = function({ times, count, processes }) {
   // Half of the statistics require the array to be sorted
@@ -50,16 +50,14 @@ const computeStats = function({ times, count, processes }) {
   const histogram = getHistogram(times, HISTOGRAM_SIZE)
 
   const mean = getMean(times)
-  const variance = getVariance(times, mean)
-  const deviation = getDeviation(variance, mean)
+  const deviation = getDeviation(times, mean)
 
   return {
     median,
     mean,
     min,
     max,
     deviation,
-    variance,
     count,
     loops,
     repeat,

src/stats/methods.js

@@ -19,18 +19,14 @@ const addNumbers = function(numA, numB) {
   return numA + numB
 }
 
-// Retrieve variance of an array of floats (cannot be NaN nor Infinite).
-// Returns Infinity when array is empty.
-export const getVariance = function(array, mean) {
-  return getMean(array.map(num => (num - mean) ** 2))
-}
-
-// Same as variance but for standard deviation.
+// Retrieve standard deviation of an array of floats (cannot be NaN/Infinity).
 // In percentage relative to the mean.
-export const getDeviation = function(variance, mean) {
+// Returns Infinity when array is empty.
+export const getDeviation = function(array, mean) {
   if (mean === 0) {
     return 0
   }
 
+  const variance = getMean(array.map(num => (num - mean) ** 2))
   return Math.sqrt(variance) / mean
 }