The analysis applied a variety of grouped data estimators and related these estimators to instrumental variables, techniques, quasi-experiments, and classical experimental design. The data covered 1977-87. Results revealed no indication that regional and time variation in DEA seizures of cocaine is helpful in explaining variation in either the demand or price of cocaine. Findings also suggest that if policymakers are interested in evaluating the efficacy of law enforcement in raising the price of cocaine to end users, passive observation of current efforts is unlikely to be adequate. Instead, it would probably be helpful to partially design both the enforcement activity and the data collection with consideration of its evaluation. Figures, tables, and 14 references (Author abstract modified)