Steve Verdon links a working paper (an updated version of which will be presented at APSA in September) by political scientists Tim Groseclose and Jeff Milyo that attempts to quantify the partisan leanings of various media outlets on the basis of their reliance on think tanks for “neutral” information in straight-news stories. Estimated ADA scores for the think tanks are derived from their citations by politicians in the Congressional Record, which are then used to estimate ADA scores for the New York Times, the Los Angeles Times, USA Today, the Drudge Report, Fox News’ Special Report, and the three broadcast network evening newscasts.

I’ve only skimmed the paper so far, but this seems like a fairly sound approach to the problem. As for the results… well, unless your name is Eric Alterman, I doubt you’ll be very surprised.