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http://www.calculator.net/standard-deviation-calculator.html As a one-liner it's really long, feel free to optimize the formatting here (or shorten it further somehow).
17 lines
590 B
Markdown
17 lines
590 B
Markdown
### Standard deviation
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Use `Array.reduce()` to calculate the mean of the values, the variance of the values, and the sum of the variance
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of the values to determine the standard deviation of an array of numbers.
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NOTE: This is **population standard deviation**. Use `/ (arr.length - 1)` at the end to
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calculate **sample standard deviation**.
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```js
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const standardDeviation = (arr, val) =>
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Math.sqrt(
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arr.reduce((acc, val) => acc.concat(Math.pow(val - arr.reduce((acc, val) => acc + val, 0) / arr.length, 2)), [])
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.reduce((acc, val) => acc + val, 0)
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/ arr.length
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);
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```
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