consumption today influences consumption tomorrow. Longitudinal data are at least very valuable and perhaps essential to disentangle the many confounding factors and understand the addictive process. As discussed throughout this report, analysis of the dynamic process of drug use, evaluation of causal risk and protective factors, the relationship between prices, enforcement, and demand, and the effect of socioeconomic conditions on the illegal drug market all benefit from valid longitudinal data.

Recently, the MTF staff announced the availability of Internet-based access to its full dataset for cross-sectional studies. These data go beyond the public-use datasets and allow for more detailed and specific analyses. However, requests to use these datasets are mediated by MTF staff, who must execute the computer programs to extract the results, review them for privacy protection, and forward them to the requesters.

The committee is concerned that even this limited kind of access is not provided for the longitudinal datasets. The committee notes that the National Center for Education Statistics has developed a system for handling sensitive school-based surveys, including its longitudinal surveys. This system allows researchers and the public online access to public-use versions of these datasets. It also extends researchers access to the full datasets upon their agreement to abide by a privacy agreement.

The committee emphasizes its serious concern for the lack of research access to the MTF panel data. Providing access to the underlying data, while ensuring appropriate protections for confidentiality, is an important objective of statistical policy. Wide access to datasets encourages use of the data and enlists the broad community of researchers in the task of analyzing and understanding current trends. Equally important is that external analysis provides the critical function of reviewing the data and the methods of those who gather the data and helps inform the research community and policy makers about the usefulness and limitations of the data. At the same time, it alerts policy makers to the need for improvements and the best applications of the results.

In our view, it is in the public interest to have full access to all data of MTF, with appropriate protection for confidentiality. The committee recommends that the Office of National Drug Control Policy and the granting agency (currently the National Institute on Drug Abuse) establish an oversight committee of statisticians and other experts, knowledgeable in procedures for balancing the needs for public access with the goal of confidentiality, to establish guidelines for providing access and for monitoring whether access to the data is quickly and easily provided.

There are a number of possible approaches that the oversight committee could recommend. One is that the National Institute on Drug Abuse undertake an agreement with the National Center for Education Statistics



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