# Dictionary:Variance

The square of the standard deviation ${\displaystyle \sigma }$, a measure of dispersion about the mean, a measure of the width of the probability distribution for a single random variable. The average squared difference of each observation from the mean.
${\displaystyle {\text{Variance}}=\sigma ^{2}=\sum {\frac {(x_{mean}-x_{i})^{2}}{n}}}$,