Age-period-cohort (APC) models are designed to estimate the independent effects of age, time periods, and cohort membership. However, APC models suffer from an identification problem: There are no unique estimates of the independent effects that fit the data best because of the exact linear dependency among age, period, and cohort. Among methods…

Research on school reform efforts and reform evaluation and the recognition that individual students are in constant transition and are members of multiple groups whose dynamics differ over the duration of schooling were examined. A conceptual framework for developing design and analysis strategies for investigating educational reform efforts is…