FreakonomicsI started to read the book Freakonomics, a book that's caused quite a stir (although it passed me by). The very first example it gives is that of a paper by Donohue and Levitt in which they claim that legalising abortion in the early 1970s cut crime in the 1990s - the type of person that has an abortion is the type of person who has children who then commit crimes. Basically, the criminals of the future were never born, so Donohue and Levitt claim.
Goertzel has used this very example in a paper, published in the Skeptical Enquirer of Econometrics as Junk Science. Donohue and Levitt used multiple regression, to find the effects of legalising abortion, controlling for other variables. But then N is, effectively, 1. Abortion was only legalised once - and that means that the correlation with any other event is 1.00, and the data are unanalysable.
As Geortzel says in his paper: "[this is] a way to model an inadequate body of data. Econometrics cannot make a valid general law out of the historical fact that abortion was legalized in the 1970s and crime went down in the 1990s. We would need at least a few dozen such historical experiences for a valid statistical test."
Apart from that, I rather liked the book. It did have some interesting examples of multiple regression, although it didn't really label them as such.