From
http://www.jrsa.org/jjec/programs/substance/Freidman, A. S., Schwartz, R., & Utada, A. (1989). Outcome of a unique youth drug abuse program: A follow-up study of clients of Straight, Inc. Journal of Substance Abuse Treatment, 6, 259-268.
The evaluation of Straight, Inc., a multimodal day treatment facility for drug abusing adolescents in Springfield, Virginia, used a pre-post design. Due to ethical considerations, all 330 participants admitted were given treatment in the facility. A substance abuse survey was administered at the beginning of treatment and at follow-up (a minimum of 6 months after graduation). Measures included self-reported delinquency and substance abuse, and psychiatric measures. The analysis compared graduates of the program to dropouts and found significant differences between the groups on prevalence of drug use.
The primary outcome measure used in this study was substance use. Substance use was measured using the Drug Severity Index, or DSI, which takes into account both the frequency of drug use and the "risk levels" of each of the various substances.