In survey research, sometimes the formation of groupings, or aggregations of cases on which to make an inference, are of importance. Of particular interest are the situations where the cases aggregated carry useful information that has been transferred from a sample employed in a previous study. For example, a school to be included in the sample of the High School Effectiveness (HSES) study must contain one or more cases transferred from the National Educational Longitudinal Study of 1988 (NELS:88). To calculate the aggregation inclusion probabilities, this study investigated three statistical models and, based on these models, derived the school weights for the HSES study. This study also assessed the effects of weighting by comparing the statistics yielded from different sets of weights: (a) those from an empirical population database and (b) those from data generated from simulation based on the principles of a superpopulation. Both categorical data and continuous variables were analyzed in the comparison.