= [(x_{i}-µ)^{2}/N]^{1/2}

where

µ is the population mean

N is the population size.

The sample estimate of the population standard deviation is computed as:

s = [(x_{i}-x-bar)^{2}/n-1]^{1/2}

where

xbar is the sample mean

n is the sample size.

See also, Descriptive Statistics Overview.