Survey estimates of drug-use trends in urban communities: General principles and cautionary examples

Surveys to depict substance abuse rates and monitor trends in specific area s have become increasingly important policy tools. Yet, as illustrated by t wo national multiwave surveys, using small sample survey data and making lo ngitudinal comparisons is fraught with interpretative problems. In the case of the metropolitan area "over-sample" of the National Household Survey on Drug Abuse, for example, interpreting apparent declines in drug use has to take account of the devastating effects of Hurricane Andrew in the Miami M etropolitan area. In the case of a 41-community survey sponsored by the Rob ert Wood Johnson Foundation to evaluate substance abuse prevention, the dif ficulty is how to interpret small differences in drug use, which seem to fo llow no reasonable pattern with respect to treatment or comparison sites. I nferences from such surveys are confounded with statistical anomalies and u nforeseen events. They are limited by the sample size. In part, the solutio n to these problems is to use other survey and nonsurvey data to validate t heir conclusions and to note their limitations. [Translations are provided in the International Abstracts Section of this issue.]