Impact evaluation studies show evidence of reduced rates of alcohol consumption and delinquent behaviors [1] [2], but except for alcohol consumption, the effects have not been sustainable in the long term [3].
The first study had a quasi-experimental design with the participation of parents of 13- to 16-year-old adolescents enrolled in secondary schools [1]. The second study conducted a randomized experiment with a sample of 2,937 students and their parents in 152 classes in 19 high schools in the Netherlands. Data was collected at the beginning of the first year of high school, before the intervention, and again 34 months later [2]. The third study was a cluster randomized experiment and had a sample size of 1,752 7th-graders and 1,314 parents. The students were enrolled in 40 municipal schools in 13 counties in Sweden [3].