WWC Review Process and Key Review Standards
The What Works Clearinghouse (WWC) evaluates the strength of the evidence of effectiveness of educational interventions. As part of the Institute of Education Sciences' (IES) plan to help educators and education policymakers incorporate scientifically based research into their educational decisions, the WWC has established rigorous standards for the review of causal research. The first set of these standards is for the review of individual studies.
WWC Evidence Standards
The WWC Evidence Standards identify studies that provide the strongest evidence of effects: primarily well conducted randomized controlled trials and regression discontinuity studies, and secondarily quasi-experimental studies of especially strong design.
"Meets Evidence Standards"--randomized controlled trials (RCTs) that do not have problems with randomization, attrition, or disruption, and regression discontinuity designs that do not have problems with attrition or disruption.
"Meets Evidence Standards with Reservations"--strong quasi-experimental studies that have comparison groups and meet other WWC Evidence Standards, as well as randomized trials with randomization, attrition, or disruption problems and regression discontinuity designs with attrition or disruption problems.
"Does Not Meet Evidence Screens"--studies that provide insufficient evidence of causal validity or are not relevant to the topic being reviewed.
In addition, the standards rate other important characteristics of study design, such as intervention fidelity, outcome measures, and generalizability.
The WWC regularly updates the WWC Technical Standards and their application to take account of new considerations brought forth by experts and users. Such changes may result in re-appraisals of studies and/or interventions previously reviewed and rated. The current WWC Standards offer guidance for those planning or carrying out studies, not only in the design considerations but the analysis and reporting stages as well. The WWC Standards, however, may not pertain to every situation, context, or purpose of a study and will evolve.