A small variance example: sample vs. population (2)

1 Name: Nameless : 2026/11/03 17:24

A quick example helps show why the denominator matters. For measurements 8, 10, 10, and 12, the mean is 10 and the squared deviations sum to 8. If those four values are the whole group, population variance is 8/4 = 2 and population standard deviation is √2 ≈ 1.41. If they are a sample used to estimate a larger process, sample variance is 8/(4−1) ≈ 2.67 and sample standard deviation is ≈ 1.63.

The standard deviation is in the same units as the measurements; variance is in squared units. For quality control, also keep the order of measurements and any time trend in view—a single spread number can hide drift.

For a larger list, this variance calculator can help check the arithmetic: https://statscalculator.org/variance-calculator/

2 Name: Nameless : 2026/11/03 18:16

But what's the centroid of a fractal?

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