This paper introduces a simple, quotient effect size, termed (for 'quotient'), suitable for reporting on the effectiveness of educational interventions. The quotient effect size for a pre-test-post-test design is defined as the gain score (i.e. post-test minus pre-test) for the intervention group, divided by the gain score for the control group.…

The What Works Clearinghouse (WWC) identifies existing research on educational interventions, assesses the quality of the research, and summarizes and disseminates the evidence from studies that meet WWC standards. The WWC aims to provide enough information so educators can use the research to make informed decisions in their settings. This…

Education decisionmakers need access to the best evidence about the effectiveness of education interventions, including practices, products, programs, and policies. It can be difficult, time consuming, and costly to access and draw conclusions from relevant studies about the effectiveness of interventions. The What Works Clearinghouse (WWC)…

We present an aggregation scheme that increases power in randomized controlled trials and quasi-experiments when the intervention possesses a robust and well-articulated theory of change. Intervention studies using longitudinal data often include multiple observations on individuals, some of which may be more likely to manifest a treatment effect…

Context: Assessments of baseline equivalency of intervention and control groups, "balance," play a critical role in evaluating educational interventions. The highest What Works Clearinghouse (WWC) of the Institute of Educational Studies (IES) standard for educational studies, "Meets WWC Design Standards Without Reservations,"…

Underlying all What Works Clearinghouse (WWC) products are WWC Study Review Guides, which are intended for use by WWC certified reviewers to assess studies against the WWC evidence standards. As part of an ongoing effort to increase transparency, promote collaboration, and encourage widespread use of the WWC standards, the Institute of Education…

The What Works Clearinghouse (WWC) is an initiative of the U.S. Department of Education's Institute of Education Sciences (IES), which was established under the Education Sciences Reform Act of 2002. It is an important part of IES's strategy to use rigorous and relevant research, evaluation, and statistics to improve the nation's education system.…

Objective: School refusal is a psychosocial problem associated with adverse short- and long-term consequences for children and adolescents. The authors conducted a systematic review and meta-analysis to examine the effects of psychosocial treatments for children and adolescents with school refusal. Method: A comprehensive search process was used…

Social cognitive theory (SCT) is a well-known theory for designing nutrition education and physical activity programs for adolescents. This systematic review aimed to evaluate the efficacy of intervention studies based on SCT in reducing or preventing overweight and obesity in adolescents. An electronic literature search in PubMed-Medline, Web of…

Background: Quasi-randomization might expedite recruitment into trials in emergency care settings but may also introduce selection bias. Methods: We searched the Cochrane Library and other databases for systematic reviews of interventions in emergency medicine or urgent care settings. We assessed selection bias (baseline imbalances) in prognostic…

Evaluating the impact of complex whole-school interventions (CWSIs) is challenging. However, what evidence there is suggests that school leadership and other elements of whole-school contexts are important for pupils' attainment (Leithwood et al., 2006), suggesting that interventions aimed at changing these have significant potential to improve…

Persons with mental illness smoke at rates two to four times higher than do persons without mental illness and comprise 30.9% of the U.S. tobacco market. Given the prevalence of mental illness and the known detrimental effects of tobacco, concerted efforts are needed to promote the use of evidence-based treatment options. We conducted a systematic…

In this article, we discuss research supporting the Strategic Instruction Model's™ (SIM) effort to address higher order reasoning and thinking skills in two lines of programmatic research. We review the extant body of evidence supporting the two lines of the SIM library, the Content Enhancement Routines and a comprehensive reading program, and the…

Pre-schoolers are in a window period for motor skill development. Visual-motor integration (VMI) is the foundation for academic and sport skills. Therefore, it must develop before formal schooling. This study attempted to improve VMI skills. VMI skills were measured with the "Beery-Buktenica developmental test of visual-motor integration 6th…

This document provides step-by-step instructions on how to complete the Study Review Guide (SRG, Version S3, V2) for single-case designs (SCDs). Reviewers will complete an SRG for every What Works Clearinghouse (WWC) review. A completed SRG should be a reviewer's independent assessment of the study, relative to the criteria specified in the review…