Variance is the difference in values of data points in a sample or population. Many often refer to variance as the spread or dispersion of the data in a sample or population.

Technically, varinace is the square of the standard deviation of a sample or population. It is calculated as follows:

variance = average(sum((mean-X)^2)))

Where:

- X = the individual data points in the sample/population
- mean = the sample or population mean