A consistent body of research shows that large classes have been perceived by teachers as an obstacle to deliver quality teaching. This large-scale study sought to investigate further those differential effects by asking 1,119 teachers from 321 K-12 schools in New South Wales (Australia) their perceptions of ideal class size for a variety of…

This study addresses several methodological problems that have confronted prior research on the effect of class size on student achievement. Unlike previous studies, this analysis accounts for the hierarchical data structure of student achievement, where grades are nested within classes and students, and considers a wide range of class sizes…

This paper introduces an empirical strategy to estimate dynamic treatment effects in randomized trials that provide treatment in multiple stages and in which various noncompliance problems arise such as attrition and selective transitions between treatment and control groups. Our approach is applied to the highly influential four year randomized…