Kremling uses data from the Drug Use Forecasting (DUF) and the Arrestee Drug Abuse Monitoring (ADAM) programs to explore whether the drug estimates of DUF, using a non-probability sample, and the drug use estimates of ADAM, using a probability sample, yield different results. She finds that the drug use information in DUF and ADAM is not substantially different for marijuana, cocaine, and opiates for all sites analyzed together. Her main conclusion is that a probability sample does not produce results that are substantially different from a convenience sample. While a researcher can attempt to |