The NLAES featured a complex multistage design (Massey et al. 1989). Primary sampling units (PSUs)1 were stratified according to sociodemographic criteria and were selected with probability proportional to size. The NLAES sample included approximately 200 PSUs, 52 of which were self-representing—that is, selected with certainty.2 Within PSUs, geographically defined secondary sampling units, called segments, were selected systematically for each sample. Because blacks experience higher rates of alcohol-related disease (e.g., liver cirrhosis) than do other population subgroups, oversampling of the black population was accomplished at this stage of sample selection.
