James Joyner takes issue with this study:
Prediction is really an odd way to judge political pundits since guessing the future is a mug’s game. … The thing that separates a good pundit from a hack is the ability to analyze facts in an illuminating framework and a willingness to adjust his view as new information comes in.
Megan McArdle makes some of the same criticisms and compares pundits to hedge fund managers:
The study runs for a little over a year, between September 2007 and 2008. … If you were the sort of person who is systematically biased towards predicting a bad end for Republicans, and a rosy future for Democrats, then election year 2008 was going to make you look like a genius.
The Dish 