Great post at American Scientist about how Freakonomics has gone off the rails.

In our analysis of the Freakonomics approach, we encountered a range of avoidable mistakes, from back-of-the-envelope analyses gone wrong to unexamined assumptions to an uncritical reliance on the work of Levitt’s friends and colleagues. This turns accessibility on its head: Readers must work to discern which conclusions are fully quantitative, which are somewhat data driven and which are purely speculative.

I loved their first book, but as the author says, the strongest part was around Levitt’s own peer reviewed research. As they’ve gotten further away from that over the years, the methodology has become a lot more hear say and writing to a deadline.