Groseclose and Milyo based their research on a standard gauge of a lawmaker's support for liberal causes. Americans for Democratic Action (ADA) tracks the percentage of times that each lawmaker votes on the liberal side of an issue. Based on these votes, the ADA assigns a numerical score to each lawmaker, where "100" is the most liberal and "0" is the most conservative. After adjustments to compensate for disproportionate representation that the Senate gives to low‑population states and the lack of representation for the District of Columbia, the average ADA score in Congress (50.1) was assumed to represent the political position of the average U.S. voter.

Groseclose and Milyo then directed 21 research assistants \ufffd most of them college students \ufffd to scour U.S. media coverage of the past 10 years. They tallied the number of times each media outlet referred to think tanks and policy groups, such as the left-leaning NAACP or the right-leaning Heritage Foundation.

Next, they did the same exercise with speeches of U.S. lawmakers. If a media outlet displayed a citation pattern similar to that of a lawmaker, then Groseclose and Milyo's method assigned both a similar ADA score.

I'm not sure how that methodology is a good way to find bias. For instance, most of the mentions one hears of the ACLU in the news is due to "conservative" groups attacking it. This methodology would seem to take that as being a story that is left-of-center because the ACLU was mentioned. I don't think they actually did that - or I would be surprised if they did - but I'd like to see the paper.

It would be interesting to see the same methodology applied to the news based on rankings of the [link|http://www.eagleforum.org/|Eagle Forum]....

FWIW, I think that whether one finds the press liberal or conservative depends on what one defines a moderate or mainstream person as. I don't think that most people base their view on what liberal or conservative is on the ADA ranking of their representative in congress.

It looks like it's already been picked apart on the blogs. E.g. [link|http://itre.cis.upenn.edu/~myl/languagelog/archives/001169.html|one criticism] and the authors' [link|http://itre.cis.upenn.edu/~myl/languagelog/archives/001301.html|response]. I've only skimmed these articles thus far - but it looks like they've tried to address my initial concerns.

The final, refereed, paper should be food for thought though. Thanks.

Cheers,
Scott.