[agallant]

So, you're saying because past research has been correlated with causality fallacies, we should just assume it's the case when we see claims of this sort? ;)

More seriously - I'm well aware of the difficulties of causality, and also use causal direction as a great illustration of them. As I've said in pretty much every comment here - I'm not championing the study, I simply haven't done a deep enough pass to have a strong opinion, and it may have any number of subtle flaws (off the cuff my biggest concern is that they're focused on one city, and I'd like to see similar results elsewhere, preferably in different geographic areas and cultures).

In other words, yes - more controls like you said. But I am responding to the overuse of a simple statistical argument in the face of studies that, whatever flaws they have, are not cases of "the researcher forgot the controls." Demographics, income, and homeownership are actually not bad features to have I'd say, and again it seems like most of the large claims bothering people are from the coverage and not the research. To refute research you generally need to dig into the details of the research itself.