The sample size estimation is based on a 10% reduction
in binge drinking occasions in the preceding 30 days
in the experimental group compared with the control
group. Since adolescents will be nested in schools a
CRCT is needed. Using a conservative approach with an
effect size of 0.2, an ICC of 0.02, power of .80, significance
level of 0.05, and considering drop-out of 50% of
adolescents at primary follow-up, we aim to include 34
schools at baseline.