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…

Reviewing complex interventions is challenging because they include many elements that can interact dynamically in a nonlinear manner. A systems perspective offers a way of thinking to help understand complex issues, but its application in evidence synthesis is not established. The aim of this project was to understand how and why systems…

Systematic reviews and meta-analyses are essential for drawing conclusions regarding etiologic associations between exposures or interventions and health outcomes. Observational studies comprise a substantive source of the evidence base. One major threat to their validity is residual confounding, which may occur when component studies adjust for…

Despite research investment and a growing body of diverse evidence there has been no comprehensive review and grading of evidence for public health emergency preparedness and response practices comparable to those in medicine and other public health fields. The National Academies of Sciences, Engineering, and Medicine convened an ad hoc committee…

In narrative synthesis of evidence, it can be the case that the only quantitative measures available concerning the efficacy of an intervention is the direction of the effect, that is, whether it is positive or negative. In such situations, the sign test has been proposed in the literature and in recent Cochrane guidelines as a way to test whether…

Inconsistent reporting of critical facets of classroom interventions and their related impact evaluations hinders the field's ability to describe and synthesize the existing evidence base. In this essay, we present a set of reporting guidelines intended to steer authors of classroom intervention studies toward providing more systematic reporting…

This research brief is one of a series of six briefs, which provide an overview of available evidence shown in the Campbell-UNICEF Mega-Map of the effectiveness of interventions to improve child wellbeing in low- and middle-income countries (LMICs). Five of the six briefs summarize evidence as mapped against the five Goal Areas of UNICEF's…

This research brief is one of a series of six briefs, which provide an overview of available evidence shown in the Campbell-UNICEF Mega-Map of the effectiveness of interventions to improve child wellbeing in low- and middle-income countries (LMICs). Five of the six briefs summarize evidence as mapped against the five Goal Areas of UNICEF's…

This research brief is one of a series of six briefs, which provide an overview of available evidence shown in the Campbell-UNICEF Mega-Map of the effectiveness of interventions to improve child wellbeing in low- and middle-income countries (LMICs). Five of the six briefs summarize evidence as mapped against the five Goal Areas of UNICEF's…

This research brief is one of a series of six briefs, which provide an overview of available evidence shown in the Campbell-UNICEF Mega-Map of the effectiveness of interventions to improve child well-being in low- and middle-income countries. Five of these briefs summarize evidence as mapped against the five goal areas of UNICEF's 2018-2021…

This research brief is one of a series of six briefs, which provide an overview of available evidence shown in the Campbell-UNICEF Mega-Map of the effectiveness of interventions to improve child wellbeing in low- and middle-income countries (LMICs). Five of the six briefs summarize evidence as mapped against the five Goal Areas of UNICEF's…

This systematic review investigated one systematic approach to designing, implementing, and evaluating functional assessment-based interventions (FABI) for use in supporting school-age students with or at-risk for high-incidence disabilities. We field tested several recently developed methods for single-case design syntheses. First, we appraised…

The purpose of this review was to synthesize the research underlying group contingency interventions to determine whether there is sufficient evidence to support their use for managing the classroom behavior of students with behavioral difficulties. An application of the What Works Clearinghouse (WWC) procedures for evaluating single-subject…

Motor vehicle safety and tobacco control are among the greatest public health achievements of the 20th century, according to the Centers for Disease Control and Prevention. As the number of miles traveled in the United States multiplied 10 times from the 1920s to the 1990s, the annual motor vehicle crash death rate per vehicle mile traveled…

Systematic reviews and meta-analysis are techniques for synthesizing primary empirical studies to produce a summary of effects. To facilitate this goal, the Campbell Collaboration (C2) supports reviews within the disciplines of crime and justice, education, international development, and social welfare. At the annual Campbell Colloquium, experts…