An appropriate estimate of statistical power is critical for the design of intervention studies. Although the inclusion of a pretest covariate in the test of the primary outcome can increase statistical power, samples selected on the basis of pretest performance may demonstrate range restriction on the selection measure and other correlated…

A subset of students fail to respond adequately to reading interventions. This synthesis systematically reviews studies in which students in grades K-3 responded inadequately to a Tier 2 reading intervention and were provided with a Tier 3 intervention. Descriptions of the Tier 3 reading interventions and effects are provided. To meet inclusion…

This paper provides causal evidence to answer the question, "Does the application of a double dose of literacy instruction in middle school improve student performance on subsequent academic outcomes?" The focus of this paper is on an intervention where the second dose of literacy instruction uses research-based instructional strategies,…

This article examines theoretical and empirical issues related to the statistical power of impact estimates under clustered regression discontinuity (RD) designs. The theory is grounded in the causal inference and hierarchical linear modeling literature, and the empirical work focuses on common designs used in education research to test…

Pretest-posttest experimental designs are often used in randomized control trials (RCTs) in the education field to improve the precision of the estimated treatment effects. For logistic reasons, however, pretest data are often collected after random assignment, so that including them in the analysis could bias the posttest impact estimates. Thus,…