Randomization and concealment
HD
RECRUITMENT, HOLIDAY, BLIND
Participants were individually randomized to either the wilderness or holiday program by means of a Random Allocation Software Program using a random block size of two. Three age groups (16–19, 20–30, 31–39 years) and gender (male/female) were used as stratification factors to achieve an equal distribution between the two arms. Separate randomization lists were generated per strata. Allocation concealment was guaranteed since the randomization and assignment of participants to the two arms were performed independently by the first author (MCJ), who was not involved in participant recruitment. Although it was not possible to blind for the intervention, participants were informed that the study aimed to investigate two possible effective interventions, not revealing which intervention was hypothesized to be the most effective one. Furthermore, the statistical outcome analyses were performed by the second author (HD) who was blind to program allocation.