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Accounting for class effect using the TIMSS 2003 eighth-grade database: Net effect of group composition, net effect of class process, and joint effect

In the scientific literature, the debate around the school and class effect is polarized, because the variance between schools and classes is explained either by school and class process or by group composition. The first aim of this article is to shed light on this debate and move beyond it by reviewing qualitative and quantitative studies showing how managerial and pedagogical process are connected to group composition. After that, a technique of models rotation is applied to the TIMSS 2003 dataset of 4 OECD countries to estimate the net effect of group composition, the net effect of class process, and the joint effect of these 2 dimensions. These 4 education systems (Belgium Flemish, England, The Netherlands, and the United States of America) have been selected because they are characterized by a strong between-classes variance. The results suggest that the joint effect of group composition and class processes, like class climate, explains a significant part of the between-class variance. The implications of these results for educational effectiveness research (EER) are discussed.