Time trends in tobacco use and its precursors
| Outcomes | Change in outcome over time | |
| γ Coefficient (SE)* | p Value | |
| Smoking index | 0.268 (0.019) | 0.001 |
| Intention to smoke | 0.130 (0.019) | 0.001 |
| Friends smoking | 0.177 (0.019) | 0.001 |
| Perception of smoking prevalence in the same grade | 0.207 (0.019) | 0.001 |
| Positive social consequences | 0.003 (0.019) | 0.854 |
| Negative social consequences | −0.237 (0.019) | 0.001 |
| Positive health consequences | −0.041 (0.020) | 0.041 |
| Negative health consequences | −0.055 (0.019) | 0.006 |
| Pro-tobacco industry attitude | 0.012 (0.019) | 0.518 |
| Anti-tobacco industry attitude | −0.015 (0.019) | 0.429 |
Values are the average change in outcome index values as students moved between grades 9 and10 to grades 11 and 12.
↵* γ One-zero (γ10) in equation 2.