Created
May 17, 2023 01:36
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function average(values: number[]): number { | |
const sum = values.reduce((acc, current) => acc + current, 0); | |
return sum / values.length; | |
} | |
export function standardDeviation(values: number[]): number { | |
/** https://www.mathsisfun.com/data/standard-deviation-formulas.html | |
* 1. Work out the Mean (the simple average of the numbers) | |
* 2. Then for each number: subtract the Mean and square the result | |
* 3. Then work out the mean of those squared differences. | |
* 4. Take the square root of that and we are done! */ | |
const mean = average(values); | |
const squaredDifferences = values.map((value) => Math.pow(value - mean, 2)); | |
const differenceMean = average(squaredDifferences); | |
const result = Math.sqrt(differenceMean); | |
return result; | |
} | |
export function zScores(values: number[]): number[] { | |
// https://statisticsbyjim.com/basics/outliers/ | |
const mean = average(values); | |
const deviation = standardDeviation(values); | |
const zScores = values.map((value) => { | |
if (deviation === 0) { | |
return 0; | |
} | |
return (value - mean) / deviation; | |
}); | |
return zScores; | |
} | |
export function p50(values: number[]): number { | |
const p50Index = Math.floor(values.length / 2); | |
const smallestToBiggest = [...values].sort((a, b) => a - b); | |
return smallestToBiggest[p50Index]; | |
} |
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