Bessel's Correction - Terminology

Terminology

This correction is so common that the term "sample standard deviation" is frequently used to mean the unbiased estimator (using n − 1). However caution is needed: some calculators and software packages may provide for both or only the more unusual formulation. This article uses the following symbols and definitions:

μ is the population mean

is the sample mean

σ2 is the population variance

s_n2 is the biased sample variance (i.e. without Bessel's correction)

s2 is the unbiased sample variance (i.e. with Bessel's correction)

The standard deviations will then be the square roots of the respective variances.