Variance

Variance is a statistical measurement that describes the spread of data points in a data set. It measures how far each number in the set is from the mean (average) and thus from every other number in the set. Variance is often denoted by the symbol σ^2.

Definition

The variance of a random variable, statistical population, data set, or probability distribution is the average of the squared differences from the mean. In other words, it measures how far a set of numbers is spread out from their average value.

Calculation

The variance is calculated by taking the differences between each number in the data set and the mean, squaring the differences (to make them positive), and averaging the resulting squares.

Uses

Variance is used in statistics for a range of purposes. It is a measure of how much values in the dataset differ from the mean. The variance is also used in finance, where it can help to determine the volatility of a financial instrument or portfolio.

See also

• Standard deviation
• Mean
• Statistical dispersion
• Expected value

References

Variance Resources
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