Variance

Variance:

(1)
\begin{align} VAR(X) = \frac{{\sum\nolimits_{j = 1}^N {{{\left( {{X_j} - \bar X} \right)}^2}} }}{{N - 1}} \end{align}

where $\bar X$ is an arithmetic mean.

Variance is a square of standard deviation.

page revision: 3, last edited: 19 Jun 2011 12:44