A characterisation of a group such as the mean of a variable or an association between variables that changes for persons born at different times or places. In cross-sectional studies, this effect can give rise to inappropriate conclusions about the nature of developmental change. A well-worn example is finding that IQ appears to decline with age from early adulthood onward when, in fact, younger cohorts tend to have higher mean IQs than older ones as a consequence of better nutrition, schooling and the like (something known as the Flynn effect).<\/p>\n
See Cohort<\/a>, Cross-sectional design<\/a>, Crystallised intelligence, Fluid intelligence<\/a>, Flynn effect<\/a>, Longitudinal design<\/a>, Longitudinal studies<\/a>, Multiple cohort study<\/a>, Period effect<\/a><\/p>\n <\/body><\/html><\/p>\n","protected":false},"excerpt":{"rendered":" A characterisation of a group such as the mean of a variable or an association between variables that changes for persons born at different times or places. In cross-sectional studies, this effect can give rise to inappropriate conclusions about the nature of developmental change. A well-worn example is finding that IQ appears to decline with … <\/p>\n