NCJ Number
219228
Journal
Forensic Science Communications Volume: 9 Issue: 2 Dated: April 2007 Pages: 1-12
Date Published
April 2007
Length
12 pages
Annotation
This study tested the hypothesis that self-reported cocaine use will parallel the outcomes of both urine and hair assays for cocaine regardless of the subject's race.
Abstract
The hypothesis was supported, which undermines persistent arguments that hair-assay methods for detecting cocaine use are racially biased against African-Americans. The ratios for all assays compared with self-reports were consistent across their respective time frames, and none of the ratios were significantly different from one another. Although a superficial inspection of the data may seem to indicate a race bias for hair analysis, indepth analysis determined otherwise. The ratios of all of the Bayes posterior probabilities were in the same direction, i.e., that being African-American was associated with a relatively higher probability of being assay-positive; however, being African-American was also associated with a higher probability of self-reported cocaine use in both short and long time frames. The hair and urine specimens along with self-report data on cocaine use were collected during the operation of the Pinellas County Drug Study (Florida), a drug-monitoring program conducted at the Pinellas County Jail from 1991 through 1993. Approximately twice a year the project staff interviewed close to 300 male and female arrestees at the booking stage of arrest. The data analyzed comprised a base of 1,857 cases. Of those asked, 92.9 percent provided a urine sample, and 84.9 percent provided a hair sample. There were no notable differences in rates of self-reported responses. The analysis compared the ratio of the probability of having a positive outcome for all three measures: self-report, urine assay, and hair assay. Researchers used an analysis based on the application of Bayes' theorem. 4 tables and 26 references