Christakis and Fowler reply.
Coincidentally, a couple weeks ago an epidemiologist was explaining to me the differences between the Framingham Heart Study and the Nurses Health Study and why Framingham got the postmenopausal supplement risks right while Nurses got it wrong.
P.S. The journal issue also includes a comment on “A distribution-free test of constant mean in linear mixed effects models.” Wow! I had no idea people still did this sort of thing. How horrible. But I guess that’s what half-life is all about. These ideas last forever, they just become less and less relevant to people.