<P> The use of n − 1 instead of n in the formula for the sample variance is known as Bessel's correction, which corrects the bias in the estimation of the population variance, and some, but not all of the bias in the estimation of the sample standard deviation . </P> <P> It is not possible to find an estimate of the standard deviation which is unbiased for all population distributions, as the bias depends on the particular distribution . Much of the following relates to estimation assuming a normal distribution . </P> <Table> <Tr> <Td> </Td> <Td> This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations . Please help to improve this article by introducing more precise citations . (December 2014) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations . Please help to improve this article by introducing more precise citations . (December 2014) (Learn how and when to remove this template message) </Td> </Tr>

Prove that s is a biased estimator of sigma