The motivation for this paper is the authors' recent work on several randomized control trials in which they found the primary result, which averaged across subgroups or sites, to be moderated by demographic or site characteristics. They are led to examine a distinction that the Institute of Education Sciences (IES) makes between "confirmatory"…

Randomized trials of educational interventions often face logistical hurdles (Cook, 2002). For example, sometimes they are prevented from reaching their full-term. This would happen if, as a condition of participation, subjects insist on receiving the treatment program within a certain timeframe. This timeframe may be shorter than the full-term…

The study examined the effects of the U.S. Department of Education's Student Mentoring Program (SMP) on students' interpersonal relationships, academic outcomes, and delinquent and risk behaviors. The study focused on approximately 2,600 at-risk fourth-through- eighth-grade students in 32 SMP sites. Applicants were randomly assigned to a program…