Associations With Changes in Students’ Mental Health and Well-Being
REGRESSIONS
These explorations were undertaken for cohorts 1 and 2 separately. Both cohorts included student- and school-level factors (student-level characteristics related to the home environment and friendships were explored in cohort 2 only). We fitted 3-level mixed-effects linear regressions, using maximum likelihood estimation in 2 steps. First, we examined 1 factor at a time for each outcome. If the inclusion of the time-by-factor term provided both a significant coefficient for the interaction and a better model fit (likelihood ratio test), compared with models with only the main effects (time and the factor), this evidenced that the factor-outcome association changed between T3 and T4. Second, to evaluate unique associations, we fitted multivariable models, entering those factors (and interactions, if relevant) that provided statistically significant 