It is too much to expect that any single omnibus sample design should be able to serve all needs effectively. It has often been suggested, in other settings, that data systems designed for specific purposes could be linked (National Research Council, 1995; Charles, 2000). In fact, federal agencies responsible for gathering data to monitor trends in drug use demonstrate a clear appreciation of the importance of linking data samples collected at different times. Careful linkage of data from one reporting period to the next promotes ready interpretation of upward or downward trends when warranted by the validity and precision of the data (e.g., see Substance Abuse and Mental Health Administration, 1999; National Household Survey on Drug Abuse Series: H-11; Tables 2.2–2.10).
There has been less attention to linkages of drug data across different reporting systems in a manner that discloses systematic jurisdictional or geographical variation. That is, the samples for each data system often have been defined and made operational quite independently, without a plan for linking the data across systems. Each data system offers its own annual or more frequent reports, but there is little integration of the evidence from multiple data sources, even when the sources serendipitously have included the same jurisdictions or geographical areas within their samples.
Table 3.2 illustrates the nature of an overlap in recent samples for a selection of federal drug use monitoring systems. Atlanta, for example, has been included at the “primary sampling unit” level in recent samples of all five of the listed activities: NHSDA, DUF/ADAM, DAWN, the Community Epidemiology Work Group, and Pulse Check (the latter two are explained below in the section on data for early warning of drug epidemics). Baltimore has been included in all but one of the samples.
A table of this type demonstrates an opportunity for linking data sources in a manner that could promote the study of local area variation in drug use and drug policy. A synthetic analysis of data from multiple drug use monitoring systems within single jurisdictions, over time, would have certain value for local planning efforts. To some extent, the Community Epidemiology Work Group and Pulse Check activities provide for a synthesis of information from these multiple sources, as well as from state or locally sponsored monitoring activities that augment the federal data systems (e.g., see Sloboda and Kozel, 1999). This synthesis is informal and qualitative in nature rather than formal and quantitative.