Closing the Gap: Modeling Within-School Variance Heterogeneity in School Effect Studies

Effective schools should be superior in both enhancing students’ achievement levels and reducing the gap between high- and low-achieving students in the school. However, the focus has been placed mainly on schools’ achievement levels in most school effect studies. In this article, we attend to the school-specific achievement dispersion as well as achievement level in determining effective schools. The achievement dispersion in a particular school can be captured by within-school variance in achievement (?²). Assuming heterogeneous within-school variance across schools in hierarchical modeling, we identified school factors related to high achievement level and a small gap between high- and low-achieving students. Schools with a high achievement level tended to be more homogeneous in achievement dispersion, but even among schools with the same achievement level, schools varied in their achievement dispersion, depending on classroom practices.