Table 2

 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 Valueββ§ (95% CI)p Valueββ¶ (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 manufacturers0.029 (0.010 to 0.044)0.0030.009 (0.006 to 0.011)<0.001
    Brown & Williamson0.059 (0.049 to 0.069)<0.001
    Lorillard0.030 (0.187 to 0.041)<0.001
    Philip Morris0.011 (0.006 to 0.015)<0.001
    RJ Reynolds0.020 (0.016 to 0.024)<0.001
Market category
    Length (⩾100 mm)0.097 (0.005 to 0.190)0.038NSNS
    Mentholated vs non-mentholated–0.043 (–0.137 to 0.051)0.367NSNS
    Candy-flavoured vs non-flavoured–0.099 (–0.194 to –0.004)0.041NSNS
    Full flavour vs non-full flavour0.348 (0.300 to 0.395)<0.0010.187 (0.155 to 0.219)<0.0010.006 (0.004 to 0.009)<0.001
    Filtered vs non-filtered–0.092 (–0.221 to 0.036)0.160NS0.002 (0.001 to 0.003)0.001
Design feature
    Nicotine concentration (mg/g)0.037 (0.032 to 0.042)<0.0010.030 (0.025 to 0.034)<0.0010.177 (0.147 to 0.207)<0.001
    Nicotine (mg) per cigarette0.061 (0.055 to 0.067)<0.001NS0.135 (0.110 to 0.161)<0.001
    Puffs per cigarette0.091 (0.079 to 0.103)<0.0010.106 (0.098 to 0.113)<0.0010.048 (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)<0.001NS
    Weight (g)1.563 (1.325 to 1.801)<0.001NSNS