Discrepant values, correlated measures: cross-city and longitudinal comparisons of self-reports and urine tests of cocaine use among arrestees

The validity of offenders' reports of illegal drug use has been challenged with data from the Drug Use Forecasting (DUF) program showing large discrepancies between arrestees' self-reports of cocaine use and the results of urine tests. The underreporting of drug use within populations, however, does not invalidate self-reports as indicators of drug use across populations if the ratio between self- reports and more objective indicators is reasonably stable. The study reported here tested this hypothesis with cross-sectional data from 13 DUF sites and longitudinal data from the St. Louis DUF program. The cross-city and longitudinal analyses both show a strong relationship between self-reports and urine tests for recent cocaine use by male arrestees that holds up under alternative model specifications and sample configurations. If these results are reproduced in subsequent research, they may have wide application in criminal justice settings and could reduce reliance on drug testing to estimate drug use for populations.