Bivariate and multivariate regression analyses of trend and determinants of nicotine yield (mg/cig) from 1998 to 2005
| Nicotine yield in smoke (mg/cig)Bivariate analyses* | Nicotine yield in smoke (mg/cig)multivariate analysis† | Market category and design time trends‡ | ||||
|---|---|---|---|---|---|---|
| ββ§ (95% CI) | p Value | ββ§ (95% CI) | p Value | ββ¶ (95% CI) | p Value | |
| cig, cigarette; NS, not significant. | ||||||
| *Each individual multilevel regression model consists of the Massachusetts (MA) regimen-measured nicotine yield as the dependent variable, and one market category, design feature or time (in years) as the independent variable. | ||||||
| †Results are given for the multilevel mixed-effects multiple regression model of MA regimen-measured nicotine yield in smoke, including all significant parameters. | ||||||
| ‡Each individual multilevel regression model consists of one market category or design feature as the dependent variable, and time as the independent variable. | ||||||
| § β-coefficients represent mg increase in nicotine yield in smoke per unit change of each parameter per year. | ||||||
| ¶ β-coefficients represent unit change of each parameter per year. | ||||||
| Time trend (years) | ||||||
| All manufacturers | 0.029 (0.010 to 0.044) | 0.003 | 0.009 (0.006 to 0.011) | <0.001 | ||
| Brown & Williamson | 0.059 (0.049 to 0.069) | <0.001 | ||||
| Lorillard | 0.030 (0.187 to 0.041) | <0.001 | ||||
| Philip Morris | 0.011 (0.006 to 0.015) | <0.001 | ||||
| RJ Reynolds | 0.020 (0.016 to 0.024) | <0.001 | ||||
| Market category | ||||||
| Length (⩾100 mm) | 0.097 (0.005 to 0.190) | 0.038 | – | NS | NS | |
| Mentholated vs non-mentholated | –0.043 (–0.137 to 0.051) | 0.367 | – | NS | NS | |
| Candy-flavoured vs non-flavoured | –0.099 (–0.194 to –0.004) | 0.041 | – | NS | NS | |
| Full flavour vs non-full flavour | 0.348 (0.300 to 0.395) | <0.001 | 0.187 (0.155 to 0.219) | <0.001 | 0.006 (0.004 to 0.009) | <0.001 |
| Filtered vs non-filtered | –0.092 (–0.221 to 0.036) | 0.160 | – | NS | 0.002 (0.001 to 0.003) | 0.001 |
| Design feature | ||||||
| Nicotine concentration (mg/g) | 0.037 (0.032 to 0.042) | <0.001 | 0.030 (0.025 to 0.034) | <0.001 | 0.177 (0.147 to 0.207) | <0.001 |
| Nicotine (mg) per cigarette | 0.061 (0.055 to 0.067) | <0.001 | NS | 0.135 (0.110 to 0.161) | <0.001 | |
| Puffs per cigarette | 0.091 (0.079 to 0.103) | <0.001 | 0.106 (0.098 to 0.113) | <0.001 | 0.048 (0.035 to 0.060) | <0.001 |
| Percentage filter ventilation | –0.013 (–0.014 to –0.011) | <0.001 | –0.014 (–0.015 to –0.013) | <0.001 | NS | |
| Weight (g) | 1.563 (1.325 to 1.801) | <0.001 | NS | NS | ||