The What Works Clearinghouse (WWC) Standards Briefs explain the rules the WWC uses to evaluate the quality of studies for practitioners, researchers, and policymakers. This brief explains what baseline equivalence is and why it matters. As part of the WWC review process for certain types of studies, reviewers assess whether the intervention group…

Educational researchers frequently study the impact of treatments or interventions on educational outcomes. However, when observational or quasiexperimental data are used for such investigations, selection bias can adversely impact researchers' abilities to make causal inferences about treatment effects. One way to deal with selection bias is to…

Nationwide, close to 40 million adults lack a high school diploma or a General Educational Development (GED) credential. About a quarter of high school freshmen do not graduate in four years, and while many high school dropouts eventually do attend GED preparation classes, too few ever pass the GED exam or go on to college. Students with only a…

Education research rarely lends itself to large scale experimental research and true randomization, leaving the researcher to quasi-experimental designs. The problem with quasi-experimental research is that underlying factors may impact group selection and lead to potentially biased results. One way to minimize the impact of non-randomization is…

This document is an appendix that is meant to accompany the main report, "Analysis of Private Returns to Vocational Education and Training". Included here are the detailed regression results that correspond to Tables 4 to 59 of the main report. This document was produced by the authors based on their research for the main report, and is…

In this set of four supplemental tables, the authors compare the baseline test scores of the treatment and matched control group samples observed in each year after KIPP entry (outcome years 1 to 4). As discussed in Chapter III, the authors used an iterative propensity score estimation procedure to calculate each student's probability of entering…

This article discusses the difficulties in conducting intervention research or evaluating intervention programs in a school setting. In particular, the problems associated with randomization and obtaining control groups are examined. The use of quasi-experimental designs, specifically a paired comparison design using the individual as his or her…

Describes how the University of Pennsylvania is testing a new way of teaching involving team-taught interdisciplinary courses on some its freshmen, while keeping others in a control group. (EV)