Population

All definitions of the population start with a definition of an individual, the elementary units about which inferences are to be drawn. The population is then the collection or aggregation of the individuals or other elements about which inferences are to be made.

In statistical usage, a population is any finite or infinite collection of individual elements. That inferences are to be made to the collection of individuals is implied by this definition. The term universe is also used in statistics for infinite or hypothetically infinite set of elements.

In survey usage, a population is strictly a finite collection of the units from which information is sought in the survey, with additional specification. The term universe is avoided, because it implies the infinite and hypothetical; survey research ...