No Significant Effects of Exposure
"Westat's analysis of the relationship between exposure to campaign advertisements and youth self-reported drug use in the NSPY [National Survey of Parents and Youth] data for the entire period covered by its evaluation -- assessments that used statistical methods to adjust for individual differences and control for other factors that could explain changes in self-reported drug use -- showed no significant effects of exposure to the campaign on initiation of marijuana by prior nonusing youth. Westat's analysis found significant unfavorable effects -- that is, a relationship between campaign exposure and higher rates of initiation -- during one round of NSPY data and for the whole period of the campaign among certain subgroups of the sample (e.g., 12-1/2- to 13-year-olds and girls). Westat found no effects of campaign exposure on rates of quitting or use by prior users of marijuana."
Government Accountability Office, "ONDCP Media Campaign: Contractor's National Evaluation Did Not Find That the Youth Anti-Drug Media Campaign Was Effective in Reducing Youth Drug Use" (Washington, DC: US Government Printing Office, August 2006), GAO-06-818, pp. 6-7.