This appendix discusses a variety of methods being developed to estimate the extent of illicit drug use in the United States. The construction of such indices is of central importance to the evaluation of drug control measures because of the need to find some way of measuring illicit drug use as the target dependent variable of government programs. We shall examine the current measures under five headings: production and sales figures; health indices, including morbidity and mortality rates and hospital admissions; indices derived from surveys covering such things as drug use and drug problems; criminal justice statistics relating to drug convictions, parole, violations, and the like; and data relating to drug tests in the civilian sector.

Some of the measures that we will consider can be used as evaluation tools in more than one way. For example, statistics regarding drug overdose deaths can be significant not just as an index of trends in drug use but also because public policies have the reduction of such deaths as their primary target. But all of the indices discussed in this appendix have also been used as part of an attempt to measure variations in the level of citizen drug use.

Production and sales

One important distinction between licit and illicit drugs concerns the availability of information from governmental regulatory and fiscal agencies that provide a sensitive and accurate index of consumption levels of licit drugs. By contrast, accurate measures of the production and consumption of illegal drugs are not available.