Changes in various cigarette design features from 2009 to 2012
| Variable | B | SE | Hypothesis test | ||
|---|---|---|---|---|---|
| Wald χ2 | df | Significance | |||
| Ventilation* | 2.33 | 0.77 | 9.178 | 1 | 0.002 |
| Pressure drop | −1.52 | 1.37 | 1.223 | 1 | 0.269 |
| Percent moisture | 0.247 | 0.193 | 1.628 | 1 | 0.202 |
| Filter density | −1.93 | 2.57 | 0.564 | 1 | 0.452 |
| Rod density | 0.27 | 2.61 | 0.010 | 1 | 0.918 |
| Tobacco weight per cigarette | −0.01 | 0.006 | 2.556 | 1 | 0.110 |
*GEE with tweedie distribution (due to significant number of zero values) and log link function.
GEE, generalised estimating equations.