What is the difference between population and sample SD?

Population SD divides by N (all values); sample SD divides by N-1 (Bessel's correction). Use population SD when you have the full dataset; use sample SD when your data is a sample from a larger population.

Variance is the square of the standard deviation. It measures the average squared deviation from the mean. Standard deviation is preferred because it is in the same units as the original data.

When is standard deviation useful?

SD is used in finance (measuring investment volatility), quality control (process variation), science (experimental error), and statistics (confidence intervals and hypothesis testing).

Standard Deviation Calculator

The Standard Deviation Calculator computes the population standard deviation and variance for a dataset of up to 5 values. Standard deviation measures how spread out values are from the mean — a low SD means values cluster close to the average, while a high SD indicates they are widely spread. It is fundamental in statistics, finance, science, and quality control.

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Frequently Asked Questions

Standard deviation (SD) measures the amount of variation in a dataset. A low SD means values are close to the mean; a high SD means they are spread out. Formula: SD = √(Σ(x - μ)² / N).

Related Calculators

🧮Variance Calculator 🧮Average Calculator 🧮Percentage Calculator