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variance ​

Problem ​

You need the variance of a dataset — the squared average deviation from the mean.

Solution ​

Use variance(array, callback?) to compute the population variance.

ts
import { variance } from '@vielzeug/arsenal';

variance([2, 4, 4, 4, 5, 5, 7, 9]); // 4

const data = [{ value: 10 }, { value: 20 }, { value: 30 }];
variance(data, (d) => d.value); // ~66.67

Pitfalls ​

  • Population variance (divide by N). Returns NaN for empty arrays.