Cohort (statistics)

In statistics, epidemiology, marketing and demography, a cohort is a group of subjects who share a defining characteristic (typically subjects who experienced a common event in a selected time period, such as birth or graduation).

Because cohort data is honed to a specific time period, it is usually more accurate.

It is more accurate because it can be tuned to retrieve custom data for a specific study.

It can be calculated as the sum of the cohort's age-specific fertility rates that obtain as it ages through time.

In contrast, the total period fertility rate uses current age-specific fertility rates to calculate the completed family size for a notional woman, were she to experience these fertility rates through her life.