Educational research on the factors of student achievement has been limited by its failure to consider the multilevel or hierarchical nature of most data. This study used a nonexperimental regression-based procedure, hierarchical linear modeling (HLM), to empirically develop a predictive model of fifth-grade achievement in reading and mathematics…

The inherent methodological problem in conducting research at multiple sites is how to best derive an overall estimate of program impact across multiple sites, best being the estimate that minimizes the mean square error, that is, the square of the difference between the observed and true values. An empirical example illustrates the use of the…