Table 3.

Average discrete change over survey wave and estimated causal effects for mental health scores, stratified by sex, among students attending 43 secondary schools with linked survey data across three waves of the COMPASS study

			Depression		Anxiety		Flourishing—reversed
			Female	Male/No response	Female	Male/No response	Female	Male/No response
Average discrete change	2019–18 (Pre)	Dif. Mean [95% CI]	1.14 [.93, 1.36]	.76 [.60, .92]	.96 [.77, 1.15]	.55 [.40, .70]	.00 [−.34, .35]	.54 [.36, .73]
	2020–19 (Per)		.33 [−.09, .74]	.64 [.24, 1.04]	.25 [−.02, .52]	.26 [−.07, .59]	−.52 [−1.10, .07]	.66 [.47, .85]
Estimated causal effect	Per - Pre	Dif.-In-Dif. [95% CI]	−.82 [−1.33, −.31]	−.11 [−.59, .36]	−.71 [−1.05, −.36]	−.29 [−.67, .09]	−.66 [−1.07, −.24]	.03 [−.46, .51]

Based on model 3: Fixed effect model controlling for time-invariant unobservables; the lagged variable is the outcome; constraining age effects on outcomes to be fixed across time and sample selection correction with predictors of selection: age, sex, weekly spending money, province, and school connectedness (predictor IMR).

Depression: CESD-10, range 0–30; Anxiety: GAD-7, range 0–21; Flourishing—reversed: Diener's 8-item Flourishing Scale, range 0–32 with lower numbers depicting higher flourishing.

CI = confidence interval; COMPASS = Cannabis use, Obesity, Mental health, Physical activity, Alcohol use, Smoking, and Sedentary behavior.