threecohort

Threecohort is a term used in research design to describe a framework in which three distinct participant groups are followed over time. The label is not tied to a single standardized methodology, and its precise definition can vary by discipline.

In a typical threecohort design, the cohorts are defined by criteria such as birth year, exposure status, or intervention group. Data are collected at multiple time points, enabling comparisons of outcomes across cohorts while attempting to separate age effects from cohort- and period-related influences. The approach can help researchers explore how historical context or different experiences shape trajectories over time.

Advantages of a threecohort design include the potential to disentangle three interacting temporal influences—age, period, and cohort—more explicitly than in simpler designs. It can offer enhanced insight into how interventions or exposures affect diverse groups. However, the design also presents challenges, including greater complexity in planning and analysis, potential confounding among cohorts, and the need for larger sample sizes to maintain statistical power across multiple groups.

Analytical methods used with threecohort data commonly involve mixed-effects or hierarchical models, survival analysis extended to multiple cohorts, and approaches that adjust for time-varying confounders. Researchers must address missing data carefully and consider the implications of unequal follow-up across cohorts.

Threecohort designs find applications across fields such as epidemiology, sociology, and market research, where comparing three distinct groups over time can illuminate differences in outcomes, risks, or behavioral patterns. See also: cohort study, longitudinal study, triple-cohort design.