Policy Perspective

Shaping Effective Drug Control Policy
by Charles F. Manski

Winter 2004, Volume 26, Number 1

Why have we as a nation been more willing to support research on public health than on drug control? Few Americans have issues with funding research on breast cancer or Alzheimer’s. We have not, however, reached this same level of consensus with respect to research on drug control. We continue to debate how much money to allocate to drug law enforcement, drug treatment, and prevention programs. Yet we have not been willing to support the research needed to make informed policy decisions.

Part of the problem is a credibility issue. In health research, randomized clinical trials (RCTs) provide a widely accepted standard for data collection and analysis. Criminal justice researchers, on the other hand, have relatively few opportunities to use RCTs. Instead, they have employed a diverse set of methods that commonly yield empirical findings of limited credibility.

To illustrate the problem, let’s consider two recent studies that contemplated the modest goal of reducing cocaine consumption by 1 percent. Both studies estimated—using different analytical approaches and data sources—the costs of achieving this objective through interdiction of drug shipments. One estimated that it would cost around $1 billion to reduce consumption by 1 percent; the other concluded that it would only cost a few tens of millions of dollars. The former study buttressed arguments that funding should be shifted toward drug-treatment programs and away from interdiction activities. The latter bolstered the point of view that interdiction should be funded at present levels or higher.

After examining the assumptions, data, methods, and findings of the two studies, the National Research Council Committee on Data and Research for Policy on Illegal Drugs, which I chaired, concluded that neither constitutes a persuasive basis for forming an effective cocaine-control policy. Both suffer from inadequate data and unjustified reasoning.

What troubles me most about both studies is their injudicious efforts to draw strong policy conclusions. It is not necessarily problematic for researchers to try to make sense of weak data and to entertain unsubstantiated conjectures. The strength of the conclusions drawn in a study, however, should always be commensurate with the quality of the evidence. When researchers overreach, they not only give away their own credibility, but they also diminish public trust in science more generally. The damage to public trust is particularly severe when researchers inappropriately draw strong conclusions about matters as contentious as drug policy.

The federal government deserves some of the blame for this predicament: Because it has made little effort to invest in data collection and analysis, the nation is in no better position to evaluate the effectiveness of drug law enforcement now than it was 20 years ago—and this will probably remain the case 20 years from now if the necessary investments are not made.

Yet social scientists are as much to blame as the federal government. True, it is difficult to use limited data to reach firm conclusions about how policy affects human behavior. But the problem runs deeper than the limitations of the available data. Prodded by a scientific community that rewards strong novel findings and a public that wants simple answers to complex issues, researchers often take great leaps of faith with their data. The result, all too often, is policy analysis that lacks credibility.

One way for researchers to enhance their credibility is to use “due caution” in policy research. Researchers need to understand their data adequately and then continually emphasize that their findings depend on their assumptions.

Whatever the government might or might not do to enrich data and support analysis, the exercise of due caution can improve the credibility of research on drug control. Making sure that this happens is the responsibility of social scientists concerned with public policy. Exercising due caution implies that we often may not be able to draw unequivocal conclusions. We may sometimes have to counsel policymakers that there is substantial ambiguity about the relative merits of alternative policies. This may be uncomfortable, but surely it is better than fooling ourselves—and the public—into thinking that we know more than we do.

Charles F. Manski is Board of Trustees Professor in Economics and an IPR faculty fellow. He was chair of the National Research Council Committee on Data and Research for Policy on Illegal Drugs from 1998 to 2001. This policy perspective draws on his commentary article in the July 2003 issue of the journal Criminology and Public Policy (www.criminologyandpublicpolicy.com). The final report of the NRC committee is available online at http://books.nap.edu/catalog/10021.html.