Did we pay for this study? (Just wondering.)
The should have standardized for geographic location, ethnicity, sex, age, &c.
The people who gave up smoking do illustrate an admirable level of self-control and determination, as well as an interest in health.
I suspect that there is also a big negative correction between tattoos and income, also. Tattoos indicate a lack of self respect, particularly for one’s person. As tattoos always run with age (and never look good on old skin), a person getting a tattoo probably manifests a short-term view, perhaps having inculcated too much of the popular “live-in-the-moment” attitude so common today among junk psychologists and phony preachers.
It was probably funded with taxes from tobacco sales.
That seems to be a common comment on all threads about studies.