John R. Lott, Jr. and Kevin A. Hassett, "Is Newspaper Coverage of Economic Events Politically Biased?"
Answer: generally, yes.
(But note to mainstream media: you'll have to be more careful from now on. Bloggers can "fact-check your ass.")
The New York Times has a piece today on the study. The piece concludes with a vicious insult of Lott by Professor Brad DeLong. Note that the insult implicitly criticizes the editors of the American Economic Review, the Journal of Political Economy, the Journal of Law and Economics, and all the other top economics journals John Lott has published in, journals that presumably wouldn't publish the work of "right wing hacks".