# Statistical sample

A

**sample** is that part of a

population which is actually observed. In normal scientific practice, we demand that it be selected in such a way as to avoid presenting a

biased view of the population. If

statistical inference is to be used, there must be a way of assigning known probabilities of selection to each sample. If the probabilities of different samples are all equal, for example, the method is called

simple random sampling.

See also: