Module 8, Chapter 2: Compositional Changes in Cluster RCTs

Module 8 of the What Works Clearinghouse (WWC) Group Design Standards Training focuses on standards related to studies that assign clusters, or groups, to conditions instead of individuals and are eligible for review using group design standards. Studies with cluster-level assignment, which we will call cluster studies, have become increasingly common in education research. The structure of these types of studies requires a special application of the WWC Group Design Standards. This module builds upon the standards discussed in earlier modules, applying concepts like attrition and baseline equivalence to cluster studies. Chapter 2 describes composition changes in cluster RCTs.

The What Works Clearinghouse is an investment of the Institute of Education Sciences (IES) within the U.S. Department of Education that was established in 2002. The work of the WWC is managed by a team of staff at IES and conducted under a set of contracts held by several leading firms with expertise in education, research methodology, and the dissemination of education research. For more than a decade, the WWC has been a central and trusted source of scientific evidence on education programs, products, practices, and policies. We review the research, determine which studies meet rigorous standards, and summarize the findings. We focus on high-quality research to answer the question “what works in education?”