The term cohort effect is used in social science to describe variations in the characteristics of an area of study (such as the incidence of a characteristic or the age at onset) over time among individuals who are defined by some shared temporal experience or common life experience, such as year of birth, or year of exposure to radiation.

Cohort effects are important to epidemiologists searching for patterns in illnesses. Certain illnesses may be socially affected via the anticipation phenomenon

Anticipation (genetics)

In genetics, anticipation is a phenomenon whereby the symptoms of a genetic disorder become apparent at an earlier age as it is passed on to the next generation. In most cases, an increase of severity of symptoms is also noted. Anticipation is common in trinucleotide repeat disorders such as...

, and cohort effects can be an indicator of this sort of phenomenon.

Cohort effects are important to resource dependency and economics theorists when these groups affect structures of influence within their larger organizations. Cohorts in organizations are often defined by entry or birth date, and retain some common characteristic (size, cohesiveness, competition) that can affect the organization. For example, cohort effects are critical issues in school enrollment.

In order to determine whether a cohort effect is present, a researcher may conduct a cohort study

Cohort study

A cohort study or panel study is a form of longitudinal study used in medicine, social science, actuarial science, and ecology. It is an analysis of risk factors and follows a group of people who do not have the disease, and uses correlations to determine the absolute risk of subject contraction...

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External links

Economics:

• Cohort Effects on Earnings Profiles

Genetics and Biology:

• Cohort effect in Lung Function among Smokers