Principal stratification provides an approach to study the effect of an exposure on an outcome within strata defined by the effect of the exposure on some third, posttreatment, variable (Frangakis & Rubin, 2002). There has been more recent interest in using principal stratification to study the extent to which the effect of an exposure on an…

The author begins this discussion by thanking Larry Hedges, the editor of the journal, for giving him an opportunity to provide a commentary on this stimulating article. He also would like to congratulate the authors of the article for their insightful discussion on causal mediation analysis, which is one of the most important and challenging…

Experimental evaluations are increasingly common in the U.S. educational policy-research context. Often, in investigations of multifaceted interventions, researchers and policymakers alike are interested in not only "whether" a given intervention impacted an outcome but also "why". What "features" of the intervention led to the impacts observed,…

Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…

This article presents the authors' rejoinder to the comments of Howard Bloom, Derek Neal, and Mike Seltzer on their article. Their commentary focused foremost on the advantages and disadvantages of using Options A, B, or C in using instrumental variables in multisite trials. Of interest are the quantities one can estimate and test in each case,…

The conventional approaches to mediation analysis such as path analysis and structural equation modeling typically involve specifying two structural models, one for the mediator and the other for the outcome. We employ an alternative approach that avoids some strong identification assumptions invoked by the conventional approaches. By applying a…

In this article I review the use of randomized field trials to evaluate school voucher interventions. I argue that although estimates of the effect of the voucher offer on achievement are unbiased in these trials, more specific interpretations such as the effect of attending private school may be difficult to obtain. I discuss several evaluation…

This article presents evidence from a large-scale randomized controlled trial of the effects of four supplemental reading comprehension curricula (Project CRISS, ReadAbout, Read for Real, and Reading for Knowledge) on students' understanding of informational text. Across 2 school years, the study included 10 school districts, more than 200…

Teacher and principal surveys are among the most common data collection techniques employed in education research. Yet there is remarkably little research on survey methods in education, or about the most cost-effective way to raise response rates among teachers and principals. In an effort to explore various methods for increasing survey response…

Early college high schools are a new and rapidly spreading model that merges the high school and college experiences and that is designed to increase the number of students who graduate from high school and enroll and succeed in postsecondary education. This article presents results from a federally funded experimental study of the impact of the…

We used a cluster randomized trial to evaluate the effectiveness of a research-based model for scaling up educational interventions, focusing on the persistence of effects with and without a follow-through intervention. The instantiation of the Technology-enhanced, Research-based, Instruction, Assessment, and professional Development (TRIAD) model…

In this commentary, the author focuses on the use of design elements for increasing the severity of causal mediation tests. The estimation of causal mediation effects from observational data rests on rather stringent assumptions. In introducing and exemplifying ratio-of-mediator-probability weighting (RMPW), Hong and Nomi (henceforth HN) make…

This study measured the effectiveness of various instructional approaches on the reading outcomes of 198 adults who read single words at the 3.0 through 5.9 grade equivalency levels. The students were randomly assigned to one of the following interventions: Decoding and Fluency; Decoding, Comprehension, and Fluency; Decoding, Comprehension,…

Results from randomized controlled trials of learning strategies instruction with 375 adult basic education participants are reported. Reading outcomes from whole group strategic instruction in 1 of 4 learning strategies were compared to outcomes of reading instruction delivered in the context of typical adult education units on social studies,…

This article reports the results from a randomized control field trial that investigated the impact of an enhanced decoding and spelling curriculum on the development of adult basic education (ABE) learners' reading skills. Sixteen ABE programs that offered class-based instruction to Low-Intermediate-level learners were randomly assigned to either…