What makes people search for Freakonomics on the web?

Bill Bennett, apparently. Or was it Good Morning America? Or World News Tonight? Or an ad in USA Today? Causality is not always easy to identify. The following chart, kindly supplied by Bill Tancer from www.hitwise.com, documents Freakonomics’ share of the web traffic from the millions of internet users that Hitwise tracks (and for fun, Bill Bennett’s too):

Last week was the highest activity we have seen to date. Many things happened last week: GMA, Bennett, World News Tonight, and a big ad that ran in USA Today. It is not completely obvious which factor was most important. Probably Good Morning America and Bennett.

That first spike in late April is from the Daily Show. The spike in mid-to-late May is from the Today show.