Variance

The variance (this term was first used by Fisher, 1918a) of a population of values is computed as:

s2 = S(xi-m)2/N

where

m

is the population mean

N

is the population size

The unbiased sample estimate of the population variance is computed as:

s2 = S(xi-xbar)2/n-1

where

xbar

is the sample mean

n

is the sample size.

See also, Descriptive Statistics.