# Variance

**
Variance
**
is the measure of statistical dispersion, that is, the variation among the different samples in a data set. It is the average of the squared differences from the
mean
.

Variance is the square of the standard deviation . If you do not know the standard deviation, you can use the following procedure to determine the variance.

### Procedure for Finding the Variance:

$1$ . Find the mean of the scores $\left(\stackrel{\xaf}{x}\right)$ .

$2$ . Subtract the mean from each individual score $\left(x-\stackrel{\xaf}{x}\right)$ .

$3$ . Square each of the differences obtained above. ${\left(x-\stackrel{\xaf}{x}\right)}^{2}$ .

$4$ . Add all of the squares obtained in step $3$ . $\left({\displaystyle \sum {\left(x-\stackrel{\xaf}{x}\right)}^{2}}\right)$ .

$5$ . Divide the total from step $4$ by the number $(n-1)$ , where $n$ is the total number of scores used.