"The deterrent effect of drug and alcohol testing was present for the index of past year illicit drug use and combined drug and alcohol use, each at two follow-up time points. If DAT were to have an impact, the expected deterrent effect likely would be that the policy would alter recent (e.g., past month) use of drugs or drugs and alcohol, since student-athletes were under the threat of testing during that time period, but not during the summer months. However, no differences were noted at any of the four follow-up time points for past month indices of use of drugs or use of drugs and alcohol. With 16 opportunities overall to demonstrate a substance-use deterrent effect during 2 years and four follow-up assessments (Table 3), only four effects were significant. The significant effects for past year drug use and alcohol and drug use were not independent, as both scales included drug use."

Source

Linn Goldberg, MD, Diane L. Elliot, MD, David P. MacKinnon, PhD, Esther L. Moe, PhD, Kerry S. Kuehl, M.D., DrPH, Myeongsun Yoon, MA, Aaron Taylor, MA, and Jason Williams, MA, "Outcomes of a Prospective Trial of Student-Athlete Drug Testing: The Student Athlete Testing Using Random Notification (SATURN) Study," Journal of Adolescent Health 41 (2007), p. 426.
http://proxychi.baremetal.com…