Characteristics of the students in the subsets.

202 students were randomised in three groups using stratification on the Grade Point Average (GPA). Students in the non-randomised group differed from the control group in the GPA and age respectively.*β = −0.53 SE = 0.17 p = 0.002.**β = 0.68 SE = 0.20 p = 0.001.n/a signifies ‘not applicable’. Re-takers of modules were automatically placed in the non-randomised group of students. Therefore, the number of this non-randomised group changed continuously and loss-to-follow-up could not be calculated. Moreover, students that stopped participating in the intervention or control groups were allocated to the non-randomised group of students.