Programs that improve teaching effectiveness represent a core strategy to improve student educational outcomes and close student achievement gaps. This article compiles empirical values of intraclass correlations for designing effective and efficient experimental studies evaluating the effects of these programs. The Early Childhood Longitudinal…

Much of the currently available evidence on the causal effects of public prekindergarten programs on school readiness outcomes comes from studies that use a regression-discontinuity design (RDD) with the age cutoff to enter a program in a given year as the basis for assignment to treatment and control conditions. Because the RDD has high internal…

This article presents evidence from a national evaluation of the effects of 21st Century Community Learning Center after-school programs. The study was conducted in 12 school districts and 26 after-school centers, at which 2,308 elementary school students who were interested in attending a center were randomly assigned either to the treatment or…