Variance Definition

In statistics, variance is a measure of how spread out data is. It is calculated as the average of the squared differences from the mean. Variance can be thought of as a measure of how much each data point deviates from the mean.

There are two types of variance: population variance and sample variance. Population variance is the true variance of a population and is usually unknown. Sample variance is an estimate of population variance and is calculated using a sample of data from the population.

Variance is used to describe how spread out data is, but it cannot be used to compare two sets of data. For example, you cannot say that one set of data has more variability than another set. To compare two sets of data, you would need to use a different statistic, such as standard deviation or range.