Hansen, William B.; Tobler, Nancy S.; Graham, John W. - In: Evaluation Review 14 (1990) 6, pp. 677-685
A meta-analysis of substance abuse prevention studies revealed that the mean proportion of subjects retained dropped from 81.4% at 3-month to 67.5% at 3-year follow-ups. Time from pretest alone accounted for less than 5% of the variance. Other available predictors of retention were not...