Despite recent shifts in research emphasizing the value of carefully designed experiments, the number of studies of teacher professional development with rigorous designs has lagged behind its student outcome counterparts. We outline a framework for the design of group randomized trials (GRTs) with teachers' knowledge as the outcome and…

This article examines the power analyses for the first wave of group-randomized trials funded by the Institute of Education Sciences. Specifically, it assesses the precision and technical accuracy of the studies. The authors identified the appropriate experimental design and estimated the minimum detectable standardized effect size (MDES) for each…

ifferent evaluation models were applied to data from a high school career education program to investigate problems in statistical conclusion validity and program effectiveness judgments. If potential threats to internal validity are analyzed and protection strategies are developed, more confidence in unplanned ex post facto design using a…

The internal validity of the RMC models, especially Model A, is examined. Concern centers on limiting evaluation to cognitive outcomes, using constant percentile as the no-treatment expectation, and using norms for one test to establish the expected no-treatment performance level for another test. (MH)