ORs with 95% CIs from generalised estimating equation (GEE) models for three outcomes
| Tobacco accessibility* | Smoking norm† | Smoking attitude‡ | |||||||
| Model 1 | Model 2 | Model 3 | Model 1 | Model 2 | Model 3 | Model 1 | Model 2 | Model 3 | |
| Time segments | |||||||||
| 2013 | Ref | Ref | Ref | Ref | Ref | Ref | Ref | Ref | Ref |
| 2014–2015 | 0.90 (0.74 to 1.09) | 0.97 (0.79 to 1.19) | 0.80 (0.64 to 0.99) | 0.86 (0.71 to 1.05) | 1.05 (0.83 to 1.33) | 0.82 (0.65 to 1.05) | 0.89 (0.71 to 1.12) | 1.10 (0.83 to 1.45) | 0.83 (0.62 to 1.11) |
| 2016–2017 | 1.11 (0.91 to 1.34) | 1.04 (0.85 to 1.27) | 0.72 (0.57 to 0.90) | 1.54 (1.27 to 1.87) | 1.53 (1.22 to 1.91) | 1.00 (0.78 to 1.29) | 1.09 (0.87 to 1.38) | 1.09 (0.83 to 1.43) | 0.67 (0.49 to 0.91) |
| School year, fourth versus second | 3.06 (2.16 to 4.34) | 2.41 (1.69 to 3.43) | 2.38 (1.67 to 3.40) | 4.07 (2.88 to 5.76) | 2.76 (1.90 to 4.00) | 2.76 (1.89 to 4.41) | 4.00 (2.57 to 6.22) | 2.71 (1.68 to 4.37) | 2.73 (1.68 to 4.43) |
| Gender, female versus male | 1.15 (0.99 to 1.33) | 1.17 (1.00 to 1.37) | 1.13 (0.97 to 1.32) | 0.75 (0.65 to 0.88) | 0.70 (0.59 to 0.83) | 0.67 (0.56 to 0.79) | 0.78 (0.65 to 0.94) | 0.75 (0.61 to 0.93) | 0.72 (0.58 to 0.89) |
| Age, per year increase | 1.20 (1.03 to 1.39) | 1.17 (1.00 to 1.36) | 1.17 (1.00 to 1.36) | 1.11 (0.96 to 1.30) | 1.07 (0.90 to 1.26) | 1.06 (0.90 to 1.26) | 1.14 (0.95 to 1.37) | 1.08 (0.87 to 1.32) | 1.07 (0.87 to 1.32) |
| Ethnicity, non-white versus white | 1.13 (0.81 to 1.56) | 1.17 (0.84 to 1.62) | 1.16 (0.84 to 1.61) | 0.87 (0.61 to 1.24) | 0.89 (0.60 to 1.33) | 0.88 (0.59 to 1.32) | 0.66 (0.42 to 1.05) | 0.59 (0.37 to 0.94) | 0.57 (0.35 to 0.93) |
| Family Affluence Scale (FAS) | |||||||||
| Low | Ref | Ref | Ref | Ref | Ref | Ref | Ref | Ref | Ref |
| Medium | 1.15 (0.96 to 1.39) | 1.21 (1.00 to 1.46) | 1.17 (0.97 to 1.42) | 1.10 (0.92 to 1.33) | 1.25 (1.01 to 1.54) | 1.21 (0.67 to 1.50) | 0.89 (0.71 to 1.11) | 1.02 (0.79 to 1.33) | 0.99 (0.76 to 1.29) |
| High | 1.18 (0.98 to 1.43) | 1.35 (1.10 to 1.65) | 1.30 (1.06 to 1.59) | 0.90 (0.74 to 1.08) | 1.20 (0.96 to 1.50) | 1.16 (0.92 to 1.45) | 0.78 (0.62 to 0.98) | 1.15 (0.88 to 1.50) | 1.09 (0.83 to 1.43) |
| Smoking status | |||||||||
| Non-(current) smoker | Ref | Ref | Ref | Ref | Ref | Ref | |||
| Current smoker | 2.08 (1.58 to 2.75) | 1.53 (1.14 to 2.05) | 4.07 (3.07 to 5.39) | 3.10 (2.31 to 4.16) | 10.3 (7.57 to 14.0) | 7.71 (5.61 to 10.6) | |||
| Family smoking | |||||||||
| None | Ref | Ref | Ref | Ref | Ref | Ref | |||
| One | 0.95 (0.78 to 1.16) | 0.88 (0.72 to 1.07) | 1.33 (1.08 to 1.63) | 1.21 (0.98 to 1.50) | 1.47 (1.13 to 1.91) | 1.34 (1.03 to 1.74) | |||
| At least two | 1.29 (1.04 to 1.60) | 1.18 (0.95 to 1.46) | 1.53 (1.22 to 1.92) | 1.37 (1.09 to 1.73) | 2.19 (1.67 to 2.87) | 1.90 (1.50 to 2.60) | |||
| Friend smoking | |||||||||
| None of them | Ref | Ref | Ref | Ref | Ref | Ref | |||
| At least some of them | 3.08 (2.58 to 3.67) | 2.62 (2.17 to 3.16) | 12.0 (9.54 to 15.1) | 10.3 (8.14 to 13.0) | 6.71 (5.04 to 8.93) | 5.67 (4.21 to 7.64) | |||
| Don’t know | 1.00 (0.74 to 1.36) | 1.00 (0.73 to 1.36) | 1.81 (1.23 to 2.67) | 1.81 (1.22 to 2.67) | 2.29 (1.48 to 3.53) | 2.30 (1.49 to 3.57) | |||
| E-cigarette use | |||||||||
| Never used | Ref | Ref | Ref | ||||||
| Used once or twice | 1.66 (1.32 to 2.09) | 1.77 (1.41 to 2.23) | 1.69 (1.27 to 2.27) | ||||||
| Current/past occasional or regular use | 3.12 (2.32 to 4.21) | 2.94 (2.16 to 4.02) | 3.38 (2.35 to 4.87) | ||||||
*Tobacco accessibility was defined as perceiving tobacco to be purchasable in shops by someone their age.
†Smoking norm was defined as perceiving that friends think it is OK for people their age to smoke.
‡Smoking attitude was defined as thinking it is OK for someone their age to smoke.