Recruiting schools and kids to participate in drug prevention evaluations is no longer, if it ever was, a "done deal." Since the mid-1980s, schools have been inundated with requirements for drug programs and requests to cooperate with program evaluations. As a consequence, both treatment and control schools are harder to find. In addition, many…

Longitudinal studies conducted with children typically experience non-response problems that can make substantial inroads on sample size and introduce bias into the analysis. Three methods for limiting non-response in school-based research programs were assessed: (1) asking parents to return consent forms only if they do not want their children to…