Statistical Population

A statistical population is a set of entities which engages our interest as a set. For example, if we were interested in generalizations about crows, then we would describe the set of crows that is of interest. Notice that if we choose a population like all crows, we will be limited to observing crows that exist now or will exist in the future. Probably geography will also constitute a limitation in that our resources for studying crows are also limited.

"Population" is also used to refer to a set of measurements, or values. Suppose, for example, we are interested in the set of all adult crows now alive in the county of Kent, and we want to know the mean weight of these birds. For each bird in the population of crows there is a weight, and the set of these weights is called the "population of weights".

In ordinary speech, "population" usually refers to a set of entities; in statistical writing, it usually refers to a set of values. In an expression such as "the mean of the population" it is obvious that the second sense is intended.

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