In statistics, a population is a set of similar items or events which is of interest for some question or experiment.
[1][2] A statistical population can be a group of existing objects (e.g. the set of all stars within the Milky Way galaxy) or a hypothetical and potentially infinite group of objects conceived as a generalization from experience (e.g. the set of all possible hands in a game of poker).
[3] A common aim of statistical analysis is to produce information about some chosen population.
[6] The population mean, or population expected value, is a measure of the central tendency either of a probability distribution or of a random variable characterized by that distribution.
, the mean is equal to the sum over every possible value weighted by the probability of that value; that is, it is computed by taking the product of each possible value
[8][9] An analogous formula applies to the case of a continuous probability distribution.