Statistics & Probability
Intermediate

Variance

Average squared deviation from the mean.

Formula

σ2=1n∑i=1n(xi−xˉ)2\sigma^2 = \frac{1}{n}\sum_{i=1}^{n}(x_i - \bar{x})^2

Variables

x_iData values
\bar{x}Mean
nCount

Example

For 2, 4, 6 (mean 4): σ² = (4+0+4)/3 ≈ 2.67.

Did You Know?

Variance squares the deviations so positives and negatives can't cancel out.

variancespreadstatistics