August 23, 2007

Smoking Statistical Soup

I have no idea what this chart means. It was offered, in another forum, to prove that poor people smoke more than rich people do (and therefore that a tax on cigarettes is regressive). But as far as I can tell, it doesn't say that. It seems to correlates rates of quitting smoking with states that have lower levels of income inequality. In other words, if there is a large gap between rich and poor in your state, you are less likely to quit smoking.

I think. There's so much statistical gobbledygook, and so much technical language, that it's entirely possible that "greater levels of income inequality" might mean "greater levels of poverty," and information about the number of people who quit smoking does not really illuminate the issue of how many people smoke in the first place, and if so, how much they smoke.

Empirically, the claim that the richer a person is, the less likely that person is to smoke seems about right. I read a book once written from the point of view of a sneering middle-class twenty-year-old that "Poor people love all the things that keep them poor, like children and cigarettes." It seemed uncharitable at the time, but it's certaintly true that a smoking habit is an expensive one and it is getting more so as tobacco taxes rise.

But an empirical observation is one thing, a statistical analysis is another. And this bit of evidence is absolutely impenetrable to me. I guess statisticians don't have to take "clear writing" classes -- but they should.

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