Variance
The average of the squared differences from the mean.
Variance quantifies how far a set of numbers spreads out from their mean by averaging the squared deviations from that mean. Squaring keeps negative and positive deviations from cancelling and weights larger deviations more heavily. Its square root is the standard deviation, which is in the same units as the data. As with standard deviation, divide by N for a population and by N−1 for a sample.