caine consumption. The study makes many unsubstantiated assumptions about the processes through which cocaine is produced, distributed, and consumed. Plausible changes in these assumptions can change not only the quantitative findings reported, but also the main qualitative conclusions of the study. Hence the study's findings do not constitute a persuasive basis for the formation of cocaine control policy.
The IDA study is best thought of as a descriptive time-series analysis of statistics relevant to analysis of the market for cocaine in the United States. The study makes a useful contribution by displaying a wealth of empirical time-series evidence on cocaine prices, purity, and use since 1980. Efforts to understand the operation of the market for cocaine must be cognizant of the empirical data. The IDA study presents many of those data and calls attention to some intriguing empirical associations among the various series.
However, the IDA study does not yield useful empirical findings on the cost-effectiveness of interdiction policies to reduce cocaine consumption. Major concerns about data and methods make it impossible to accept the IDA findings as a basis for the assessment of interdiction policies. Numerous problems diminish the credibility of the cocaine price series developed in the study, and an absence of information prevents assessment of the procedure for selecting interdiction events. The conclusions drawn from these data rest on the assumption that all time-series deviations in cocaine price from an exponential decay path should be attributed to interdiction events, not to other forces acting on the market for cocaine. This foundation is too fragile to support the study's conclusions or to serve as a basis for policy.
The process of scrutinizing the specifics of the RAND and IDA studies has helped the committee to frame the questions that it will now address in a broad study of how data and research may, in the future, better serve the objective of informing drug control policy.