Table 1 Observed and adjusted cannabis use means, discrete change of cannabis use indicators over survey waves, and estimated causal effect of COVID-19 on cannabis use by difference-in-difference among eligible students attending the 43 linked-longitudinal COMPASS schools across the three study waves (2018, 2019, 2020)
Cannabis Use | ||||||||
|---|---|---|---|---|---|---|---|---|
Monthly Use | Weekly Use | Daily Use | ||||||
Wave | N | Observed Mean (SD) | Adjusted Estimatea Mean (95% CI) | Observed Mean (SD) | Adjusted Estimatea Mean (95% CI) | Observed Mean (SD) | Adjusted Estimatea Mean (95% CI) | |
Observed and Adjusted Outcome Mean | 2018 | 7567 | 5.7 (0.2) | 5.7 (4.9, 6.5) | 2.4 (0.2) | 2.4 (1.8, 3.0) | 0.6 (0.1) | 0.6 (0.3, 0.9) |
2019 | 7548 | 12.1 (0.3) | 12.0 (11.0, 12.9) | 6.1 (0.2) | 6.4 (5.2, 7.6) | 1.5 (0.1) | 1.4 (1.1, 1.7) | |
2020 | 1937 | 7.5 (0.3) | 12.6 (10.7, 14.4) | 3.9 (0.2) | 7.4 (5.7, 9.2) | 0.8 (0.1) | 1.9 (1.4, 2.5) | |
Difference Mean (95% CI) | Difference Mean (95% CI) | Difference Mean (95% CI) | ||||||
Average Discrete Changeb | 2019–2018 (pre-COVID-19 period) | 6.3 (5.2, 7.4) | 4.0 (2.5, 5.4) | 0.8 (0.4, 1.2) | ||||
2020–2019 (early COVID-19 period) | 0.6 (−1.2, 2.3) | 1.0 (− 1.5, 3.5) | 0.5 (− 0.1, 1.0) | |||||
Difference-in-Difference (95% CI) | Difference-in-Difference (95% CI) | Difference-in-Difference (95% CI) | ||||||
Estimated Causal Effectb | (2020-2019) - (2019-2018) | − 5.7 (− 8.0, − 3.4) | −3.0 (− 6.7, 0.8) | − 0.3 (− 1.1, 0.4) | ||||