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Posted 02.01.05

Study Points to Bias in Major Media

COLUMBIA, Mo. - Pundits have long argued about the liberal bias of mainstream mass media outlets, presenting cases on both sides of the issue. Applying a novel approach based on frequently used ratings of the liberal or conservative leaning of politicians, a researcher at the University of Missouri-Columbia discovered that most mainstream media outlets do exhibit a strong liberal bias.

"We found that most of the mainstream media view events through a 'lens' that is very similar to that used by Democrats in Congress," said Jeff Milyo, MU associate professor of economics and public affairs. "That is, most major media outlets and Democrats cite similar sources of expertise, such as particular think tanks and advocacy groups. This suggests that popular complaints about a liberal bias in the media are well-founded."

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To determine the bias of media outlets, Milyo and colleague Tim Groseclose, a political scientist at UCLA, applied the Americans for Democratic Action (ADA) scoring system. ADA scores are used widely in political science to describe the placement of an individual member of Congress on an ideological scale, from conservative to liberal. The researchers examined the patterns by which media outlets cited particular think tanks and policy groups, and then compared these to the citation patterns of legislators with known ADA scores. This research is unique from previous studies because it does not rely upon subjective classifications, Milyo said.

"Up to this time, evidence has consisted mainly of anecdotes, or relied upon highly subjective analyses of news reports," Milyo said. "Ours is a systematic and objective test of the liberal media hypothesis."

The results demonstrate a strong liberal bias. All news outlets examined, except for Fox News' Special Report and the Washington Times, received a score to the left of, or more liberal than, the estimated position of the average U.S. voter. The scores for CBS Evening News and the New York Times were among the most liberal, while outlets such as USA Today, NPR's Morning Edition, NBC's Nightly News and ABC's World News Tonight were moderately liberal. The most neutral outlets were the Newshour with Jim Lehrer, CNN's NewsNight with Aaron Brown and ABC's Good Morning America. Fox News' Special Report, while more conservative, was closer to the center than any of the three major networks' evening news broadcasts.

The study referred strictly to the news stories of the outlets, omitting editorials, book reviews and letters to the editor, Milyo said.

Web Editor's note: A Measure of Media Bias was published in the November 2005 issue of the Quarterly Journal of Economics.



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