Cohort

The term cohort refers to a group of individuals who share a demographic experience during a defined time interval. For example, graduate students often refer to the group of students who started their doctoral program (a shared event) in the same semester (a defined time interval) as their “graduate school cohort.” Other common examples of cohorts include ones defined by birth, marriage, and geography, such as the group of persons born in 1986, the group of individuals married between 2010 and 2015, or the group of individuals who lived in Philadelphia in 2005. This entry provides an overview of cohorts, emphasizing what they contribute to a richer understanding of lifespan processes and why they create measurement challenges.

In lifespan research, the broad term cohort is often ...