2.6. Main Analyses
SECONDARY
The main analyses were performed using Stata 14 with maximum likelihood estimation. The data were normally distributed, and the latent scales were invariant over time. In order to examine the effects of the interventions, we assessed a multi-level linear mixed model that produces fixed and random effect results. The fixed effect was the impact of the interventions, while the random effect captured the residual variance. The fixed effect includes interactions between time and intervention conditions, sex, and socioeconomic status. The level of statistical significance was 0.05. It is important to note that in Norway, the school year starts in August and ends in June; therefore, life satisfaction, loneliness, and psychological distress were measured on the first measurement occasion, which took place in the beginning of year 1 (baseline), when the students had just started their upper secondary education. In contrast, teacher support, classmate support, and caring climate were first measured in the spring of year 1 (Y1), when the students had assumably gotten to know their environment, and the people within it, well enough to assess the perceived support they experienced from it.