Multilevel models are an increasingly popular method to analyze data that originate from a clustered or hierarchical structure. To effectively utilize multilevel models, one must have an adequately large number of clusters; otherwise, some model parameters will be estimated with bias. The goals for this paper are to (1) raise awareness of the…

Press reports and industry statistics both give incomplete pictures of the outcomes of the Great Recession for U.S. four-year colleges and universities. To address these gaps, we conducted a statistical analysis of all articles that appeared in Lexis-Nexis on a sample of more than 300 U.S. colleges and universities during the Recession years. We…

Experimental evaluations that involve the educational system usually involve a hierarchical structure (students are nested within classrooms that are nested within schools, etc.). Concerns about contamination, where research subjects receive certain features of an intervention intended for subjects in a different experimental group, have often led…

A common mistake in analysis of cluster randomized trials is to ignore the effect of clustering and analyze the data as if each treatment group were a simple random sample. This typically leads to an overstatement of the precision of results and anticonservative conclusions about precision and statistical significance of treatment effects. This…

Although a variety of studies have indicated that using statistical clustering techniques to examine genetic information may allow for geographically based groupings of individuals that tenuously map onto some conceptions of race, these studies have also indicated that the amount of genetic variation within these groupings is significantly larger…

Understanding that the behavior of people takes place within a context, over the past 20 years research in education and the sport sciences has witnessed an increasing development of multilevel frameworks that are both conceptually and methodologically sound. Despite these advances, the use of multilevel models and research designs in education…

Addressed to institutional researchers, this report from California's Chabot College presents information on National Center for Education Statistics (NCES) data sets. Included is a discussion on how these data sets can be used to create peer groups of U.S. colleges, and to produce statistics on major student variables for each of these groups.…