For decades, achievement goal theory has been extensively used, but empirical research still requires a clearer understanding of the underlying factors conceptualized and measured during secondary school periods. In light of the increasing use of longitudinal studies in motivation research, this study aims to investigate the longitudinal…

Growth curve models with different types of distributions of random effects and of intraindividual measurement errors for robust analysis are compared. After demonstrating the influence of distribution specification on parameter estimation, 3 methods for diagnosing the distributions for both random effects and intraindividual measurement errors…

This article illustrates the use of an explanatory item response modeling (EIRM) approach in the context of measuring group differences in science achievement. The distinction between item response models and EIRMs, recently elaborated by De Boeck and Wilson (2004), is presented within the statistical framework of generalized linear mixed models.…