What Works Clearinghouse
"The What Works Clearinghouse (WWC) collects, screens, and identifies studies of effectiveness of educational interventions (programs, products, practices, and policies).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."