## Variance ${\sigma}^{2}$

The variance ${\sigma}^{2}$
is the average of the second powers of deviations of the individual values from the arithmetic mean of the values of the statistical set.

$${\sigma}^{2}=\frac{\underset{i=1}{\overset{n}{\u2140}}{\left({x}_{i}-\overline{x}\right)}^{2}}{n}$$

- ${\sigma}^{2}$
- variance;
- $n$
- a number of elements of the statistical set;
- ${x}_{i}$
- an element of the statistical set with index
*i*;
- $\overline{x}$
- a simple arithmetic mean.

Variance is an indicator of variability.