Sample standard deviation

Scientific calculators make the computation of standard deviation
(σ) easy.

However, if the number of observations is extremely large even it becomes tedious.

In such cases, N values are taken as a sample from them and correction applied to the
formulae.

It is called Bessel's correction in which (N – 1) replaces N in the formulae of
σ^{2} and σ.

σ is specifically known as sample standard deviation.

σ^{2} =

and σ =