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 =