The explained variance increased with each step, starting with 0.4% in the first step (all steps individually can be found in Supplementary Table S6)
Some say that it's the vehicle manufacturers' attempt to save money on car parts, while others say companies do not want to be associated with tobacco tycoons and the overall proliferation of their products (via Mental Floss)
Marketing strategies include maintaining a staff of pharmaceutical sales representatives, a marketing workforce, sponsorship of continuing medical education programs and cruises, drug coupons, free drug samples, direct-to-consumer advertising, and consultant fees to physicians
It is silly because no one would stop you from using nicotine gum or a patch, one commenter added
I found that and more at GIT