Related factors to e-cigarette use by generalised estimation equation (GEE) for binary outcome (n=12 495)
| Factors | Model 1 adj. OR | 95% CI | Model 2 adj. OR | 95% CI | Model 3 adj. OR | 95% CI |
| Intrapersonal level | ||||||
| Age | 1.165 | 1.121 to 1.211 | 1.228 | 1.116 to 1.351 | 1.080 | 0.938 to 1.244 |
| Male | 1.995 | 1.688 to 2.357 | 1.687 | 1.173 to 2.426 | 1.727 | 1.160 to 2.570 |
| Positive belief towards e-cigarettes | 1.049 | 1.039 to 1.059 | 1.043 | 1.017 to 1.069 | 1.051 | 1.024 to 1.079 |
| Positive attitude towards e-cigarettes | 1.076 | 1.058 to 1.094 | 1.007 | 0.969 to 1.047 | 0.984 | 0.947 to 1.023 |
| Knowledge of e-cigarette legislation | 1.150 | 1.118 to 1.184 | 1.175 | 1.107 to 1.248 | 1.116 | 1.049 to 1.186 |
| Inter-personal level | ||||||
| E-cigarette users in a relationship | 0.949 to 2.636 | |||||
| Siblings | 1.582 | 2.485 | 1.402 to 4.404 | |||
| Girlfriend or boyfriend | 3.568 | 2.248 to 5.663 | 3.239 | 2.017 to 5.199 | ||
| Close friend | 2.729 | 1.818 to 4.095 | 2.786 | 1.844 to 4.208 | ||
| School and community level | ||||||
| Signs prohibiting e-cigarettes in school | 0.737 | 0.484 to 1.124 | ||||
| Exposure to e-cigarette use in school | 4.040 | 2.827 to 5.775 | ||||
| Types of educational institutions | ||||||
| High school | 1 | |||||
| Vocational school | 2.386 | 1.177 to 4.837 | ||||
| College/university | 2.295 | 1.129 to 4.665 | ||||
Model 1 GEE considers factors at intra-personal factors.
Model 2 GEE considers factors at intrapersonal and interpersonal levels.
Model 3 GEE considers factors at the intrapersonal, interpersonal, and school and community levels.
adj. OR, adjusted OR.