Are Simple Change Scores Obsolete? An Approach to Studying Correlates and Predictors of Change

This paper complements recent discussions about the reliability of observed change scores (Collins, 1996a; Humphreys, 1996; Williams & Zimmerman, 1996a, 1996b). It is argued that modeling change on the latent dimension of interest is a better approach to measuring change than focusing on observed change scores and their properties. It is proposed that research be directed toward correlates and predictors of ability change (Rogosa & Willett, 1985b) and away from recorded change scores and their reliability. A latent variable modeling approach is discussed that focuses on ability change scores. It permits estimation of both individual latent change scores and the relationship of ability change scores to other variables.