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…

Forty years ago, the National Center for Education Statistics initiated the national longitudinal studies program in response to congressional concern for policy-relevant information on school-to-work transitions. This program has grown substantially, and not unexpectedly, questions have arisen about its usefulness and present operation. This…