Age, cohort, and time-period confounds in aging research

1. Cross-sectional studies of age-related changes or developmental patterns contain the inherent confound of age and cohort. 2. Longitudinal studies of age-related changes or developmental patterns contain the inherent confound of age and time-period. 3. Many complex research designs and decision rules have been developed in an attempt to disentangle these confounds. These designs and decision rules are only useful if their assumptions are met. 4. It is important to logically determine when the age, cohort, and time-period confounds discussed in this article are important to resolve in a nursing study and when the confounds do not directly relate to the clinical or theoretical merit of a study.