# Variance (statistics)

> In statistics, variance is a measure of how spread out data are around the mean.

In [statistics](https://wiki.g15e.com/pages/Statistics.txt), variance is a measure of how spread out data are around the mean.

<Population variance> is $\large\frac{\Sigma(x - \mu)^2}{n}$, and <sample variance> is $\large\frac{\Sigma(x - \bar{x})^2}{n - 1}$. To use the same units as the data, we often use the [standard deviation](https://wiki.g15e.com/pages/Standard%20deviation.txt), the <square root> of the variance.

## External links

- [Calculating the Mean, Variance and Standard Deviation, Clearly Explained!!!](https://www.youtube.com/watch?v=SzZ6GpcfoQY&list=PLblh5JKOoLUK0FLuzwntyYI10UQFUhsY9&index=7)