Purpose: Multisite mediation studies are a cornerstone in mapping out developmental processes because they probe the mechanisms of a treatment while creating key opportunities to learn from and about variation in those mechanisms across sites. Despite the prevalence of multisite studies, a significant gap in the literature is how to plan such…

Introduction: The What Works Clearinghouse (WWC) reviews rigorous research on educational interventions with a goal of identifying "what works" and making that information accessible to educators and policymakers. In rating the quality of causal research, the WWC has historically prioritized internal validity over external validity. One…

Despite a history that can be tracked to 1867, the US Department of Education is a relative newcomer to applying evidence standards to education research. The What Works Clearinghouse (WWC) reviews intervention research to support evidence-based decision making. This is done by applying standards of research quality to studies and giving those…

I. Purpose of the Study: Detecting whether interventions work or not (through main effect analysis) can provide empirical evidence regarding the causal linkage between malleable factors (e.g., interventions) and learner outcomes. In complement, moderation analyses help delineate for whom and under what conditions intervention effects are most…

Background: The emergence of causal research in education was almost strictly quantitative twenty years ago, however, that landscape has changed considerably. The number of intervention studies fielded and completed annually has increased substantially, and the quality of the evaluations is much more robust, including paying much greater attention…

Background/Context: Attrition has been described as "the Achilles Heel of the randomized experiment" (Shadish et al., 1998 p.3). Attrition looms as a threat because it can undermine group equivalence, eroding the methodological strength at the heart of a randomized evaluation. In particular, attrition could result in unobserved…

Background/Context: When a researcher tests an educational program, product, or policy in a randomized controlled trial (RCT) and detects a significant effect on an outcome, the intervention is usually classified as something that "works." When the expected effects are not found, however, there is seldom an orderly and transparent…

Background/Context: Methodological background: Meta-analysis typically depends on the assumption that true effects follow the normal distribution. While assuming normality of effect "estimates" is often supported by a central limit theorem, normality for the distribution of interventions' "true" effects is a computational…

Background/Context: Some observational studies involve multiple layers of treatment selection, specifically in the context of the extended time accommodation (ETA) for English language learners (ELLs). In ETA settings, the first selection occurs due to the eligibility rule, where students whose ELL English proficiency is below a certain threshold…

Many public and private initiatives have focused on improving prekindergarten (PK) through Grade 12 mathematics education, given that the mathematics content learned before college is foundational for later learning and college success across STEM subjects. Although decades of educational research have studied PK-12 mathematics interventions, the…

Following the theme of the first two presentations, this presentation will focus on the choices available for research synthesis when summarizing research evidence. The presenters will describe the current research synthesis practice of the What Works Clearinghouse (WWC) as well as several alternative models, including inverse-variance weighted…

Background: Observation Studies, Unmeasured Confounding, and Sensitivity Analysis: An important part of educational research is identifying important, potentially causal, factors that influence children's learning from observational studies. However, it is well-known that discovering such factors from observational studies can be biased due to…

The focus of the article is the process educators use to interpret data to turn it into usable knowledge (Honig & Coburn, 2008) while engaging in a continuous improvement process. The authors examine the types of evidence educators draw upon, its perceived relevance, and the social context in which the evidence is examined. Evidence includes…

Meeting the What Works Clearinghouse (WWC) attrition standard (or one of the attrition standards based on the WWC standard) is now an important consideration for researchers conducting studies that could potentially be reviewed by the WWC (or other evidence reviews). Understanding the basis of this standard is valuable for anyone seeking to meet…

Prior reviews of evidence for the impact of formative assessment on student achievement suggest widely different estimates of formative assessment's effectiveness, ranging from 0.40 and 0.70 standard deviations in one review. The purpose of this study is to describe variability in the effectiveness of formative assessment for promoting student…