Editing Cohort (statistics) (section)

== Comparison with period data ==

Cohort data can oftentimes be more advantageous to [[Demography|demographers]] than period data. 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.{{cn|date=August 2023}}

In addition, cohort data is not affected by [[tempo effect]]s, unlike period data. However, cohort data can be disadvantageous in the sense that it can take a long amount of time to collect the data necessary for the [[cohort study]].<ref name=":02">{{Cite web|url=http://sphweb.bumc.bu.edu/otlt/MPH-Modules/EP/EP713_CohortStudies/EP713_CohortStudies5.html|title=Advantages and Disadvantages of Cohort Studies|website=sphweb.bumc.bu.edu|language=en|access-date=2018-03-27}}</ref> Another disadvantage of cohort studies is that it can be extremely costly to carry out, since the study will go on for a long period of time, demographers often require sufficient funds to fuel the study.{{cn|date=August 2023}}

Demography often contrasts [[cohort perspective]]s and [[period perspective]]s. For instance, the total cohort [[fertility rate]] is an index of the average completed family size for cohorts of women, but since it can only be known for women who have finished child-bearing, it cannot be measured for currently fertile women. 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.{{cn|date=August 2023}}