Sample size and randomization
Power calculations were performed at the employee level adjusting
for school-clustering. The sample size calculation was conducted prior
to the study to detect potential improvements in the primary outcome
with 30% among employees in the multifaceted group in contrast with
the discrete group. Based on an alpha significance level of 0.05,
desired power of ≥80%, and intraclass correlation coefficient of
0.005, approximately 400 individuals in total were required: 200 in
the multifaceted group and 200 in the discrete group. It was
calculated that this would require ≥18 schools.In total, 334 participants were included in the multifaceted group
clustered within 10 schools, whereas 364 participants were in the
discrete group clustered within 9 schools. The randomization of
schools was conducted through a computer-generated randomization-list
before the baseline measure. An independent statistician not involved
in the project performed the randomization. Neither school management
nor school personnel were blinded.