bility of such linkages is not yet clear. DAWN, after all, is a survey of events (emergency department drug-related cases) rather than of persons. The Substance Abuse and Mental Health Administration, working cooperatively with state substance abuse agencies, compiles lists of treatment facilities and periodically collects information about the number and characteristics of persons receiving treatment. There are three relevant treatment data sets:
The Drug and Alcohol Services Information System includes a national roster of treatment facilities, a census of these facilities and information about clients.
The Uniform Facility Data Set is an annual census of clients in treatment. It tracks the number and characteristics of clients in treatment as of a reference date each fall.
The Treatment Episode Data Set uses admissions records to compile information about patients in facilities receiving public funding.
These surveys, however, are primarily designed to describe the characteristics and efficacy of treatment programs. They do not include persons needing treatment who do not get it. Furthermore, they are not designed as samples of people receiving treatment, but rather provide samples of treatment episodes.
Whether the subject of interest is prevalence, frequency, or quantity consumed, questions about the quality of self-reports of drug use are inevitable. The usefulness of the data obtained from a survey is reduced if some sampled individuals fail to answer one or more questions on the survey (nonresponse) or give incorrect answers (inaccurate response). In particular, nonresponse and inaccurate response may lead investigators to draw incorrect conclusions from the data provided by a survey. Response problems occur to some degree in nearly all surveys but are arguably more severe in surveys of illegal activities. For example, some individuals may be reluctant to admit that they engage in illegal behavior, whereas others may brag about such behavior and exaggerate it.
It is widely thought that nonresponse and inaccurate response may cause surveys such as the NHSDA and MTF to underestimate the prevalence of drug use in the surveyed populations (Caspar, 1992). It is often assumed, however, that these surveys provide accurate information about trends. For example, the principal investigators of MTF state that “biases in the [MTF] survey will tend to be consistent from one year to another,