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Standard Deviation Calculator

Find the mean, variance and standard deviation of a data set.

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Sample vs. population

Standard deviation measures how spread out numbers are around the mean. Use the sample formula (dividing by n−1) when your data is a sample drawn from a larger group; use the population formula (dividing by n) when you have every member of the group.

σ = √( Σ(xᵢ − x̄)² / N )

A small standard deviation means values cluster near the mean; a large one means they are widely dispersed.