Standard Deviation Calculator

Mean, variance and standard deviation (population & sample).

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About this calculator

Population SD describes the dataset itself; sample SD estimates the larger population it was drawn from — use sample when generalizing (polls, experiments).

Formula

SD = √[ Σ(x−mean)² ÷ N ] (population) or ÷(N−1) (sample).

Frequently Asked Questions

Which SD should I report?

Descriptive work on complete data → population. Inferential work from a sample → sample.

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