This entry examines the role of randomized control trials (RCTs) in education research. A description of RCTs and the advantages they provide in estimating program effects is followed by a review of the potential problems that can arise when conducting RCTs. The next section presents a detailed discussion of a well-known example of an RCT in education policy, Project STAR, or Student/Teacher Achievement Ratio, also known as the Tennessee STAR experiment. This is followed by a comparison of the use of randomized experiments with that of nonrandom, quasi-experimental techniques and the conditions under which the two will yield similar results.

The main question most educators and policymakers ask about any program is “Does it work?” Unfortunately, evidence is often lacking and practitioners are left to rely ...