Cohort

Definition

A cohort is defined as a group of people sharing a common temporal demographic experience who are observed through time. In addition to being restricted to a common temporal demographic experience, cohorts may also be restricted based on the other geographic or demographic filters used for the population -- the key point is that the only additional restriction placed on the cohort, relative to the whole population, is based on the temporal experience.

Common types of cohorts

Cohort type	Event that has to occur within a specified time period
Birth cohort	Birth
School class cohort	Enrollment in or graduation from a particular school
Marriage cohort	Marriage