All participating schools (20 total) had a large student body, were split equally between urban and rural locations, and had comparably experienced teachers.
The control and experimental groups were similar in characteristics.
A total of 1,722 students participated in the study (754 in the control group and 968 in the intervention group).
Intervention schools had higher consent rates, possibly due to teachers’ efforts in these schools to obtain consent as a result of greater familiarity with the program from the previous pilot year.
It should be noted that those lost to follow-up versus those who completed the study were more likely to be male and to have reported alcohol problems in grade 9 (25 percent, compared to 16 percent of those who completed the study).
A 95 percent confidence interval was used to estimate effect size.
Separate analyses were conducted using the subsample of students who were dating the year before follow-up.
Students in the comparison schools received a standard Health and Physical Education curriculum in sex-segregated classrooms.
Teachers in the comparison schools were required to cover the topics of the three units being taught in the intervention schools, but without any background or training on these topics or access to a structured curriculum.
Participating students filled out information sheets, consent forms, and a demographic form for parents.
A confidential, online survey was given in school at baseline and 2.5 years later, at follow-up.