In statistics, a population consists of all members of a group of interest. Populations can vary in size and include people, animals, plants, or objects. Since studying every member of a population is impractical, a representative subset called a sample is used instead. The sample is used to represent or make assumptions about the population.

For example, suppose there is a study that examines high school students in Boston and their attitudes towards mathematics. In this case, the population consists of all high school students in Boston. Since it is impractical to study every student, a sample can be taken by using sampling methods.