John Tierney in The New York Times:
Researchers at the University of Pennsylvania have intensively studied the New York Times list of most-e-mailed articles, checking it every 15 minutes for more than six months, analyzing the content of thousands of articles and controlling for factors like the placement in the paper or on the Web home page. The results are surprising — well, to me, anyway. I would have hypothesized that there are two basic strategies for making the most-e-mailed list. One, which I’ve happily employed, is to write anything about sex. The other, which I’m still working on, is to write an article headlined: “How Your Pet’s Diet Threatens Your Marriage, and Why It’s Bush’s Fault.”
But it turns out that readers have more exalted tastes, according to the Penn researchers, Jonah Berger and Katherine A. Milkman. People preferred e-mailing articles with positive rather than negative themes, and they liked to send long articles on intellectually challenging topics. Perhaps most of all, readers wanted to share articles that inspired awe, an emotion that the researchers investigated after noticing how many science articles made the list. In general, they found, 20 percent of articles that appeared on the Times home page made the list, but the rate rose to 30 percent for science articles, including ones with headlines like “The Promise and Power of RNA.” (I swear, the science staff did nothing to instigate this study, but we definitely don’t mind publicizing the results.)
More here.