A Measure of Media Bias
Tim Groseclose
Department of Political Science, UCLA, and
Graduate School of Business, Stanford University
Jeff Milyo
Harris School of Public Policy
University of Chicago
September 2003
Do the major media outlets in the U.S. have a liberal bias? Few questions evoke stronger opinions, and we cannot think of a more important question to which objective statistical techniques can lend their service. So far, the debate has largely been one of anecdotes (“How can CBS News be balanced when it calls Steve Forbes’ tax plan ‘wacky’?”) and untested theories (“if the news industry is a competitive market, then how can media outlets be systematically biased?”).
Few studies provide an objective measure of the slant of news, and none has provided a way to link such a measure to ideological measures of other political actors. That is, none of the existing measures can say, for example, whether the New York Times is more liberal than Tom Daschle or whether Fox News is more conservative than Bill Frist. We provide such a measure. Namely, we compute an ADA score for various news outlets, including the New York Times, the Los Angeles Times, USA Today, the Drudge Report, Fox News’ Special Report, and all three networks’ nightly news shows.
Our results show a very significant liberal bias. All of the news outlets except Fox News’ Special Report received a score to the left of the average member of Congress. Moreover, by one of our measures all but three of these media outlets (Special Report, the Drudge Report, and ABC’s World News Tonight) were closer to the average Democrat in Congress than to the median member of the House of Representatives. One of our measures found that the Drudge Report is the most centrist of all media outlets in our sample. Our other measure found that Fox News’ Special Report is the most centrist. These findings refer strictly to the news stories of the outlets. That is, we omitted editorials, book reviews, and letters to the editor from our sample.
To compute our measure, we count the times that a media outlet cites various think tanks. We compare this with the times that members of Congress cite the same think tanks in their speeches on the floor of the House and Senate. By comparing the citation patterns we can construct an ADA score for each media outlet.
As a simplified example, imagine that there were only two think tanks, one liberal and one conservative. Suppose that the New York Times cited the liberal think tank twice as often as the conservative one. Our method asks: What is the estimated ADA score of a member of Congress who exhibits the same frequency (2:1) in his or her speeches? This is the score that our method would assign to the New York Times.
A feature of our method is that it does not require us to make a subjective assessment of how liberal or conservative a think tank is. That is, for instance, we do we need to read policy reports of the think tank or analyze its position on various issues to determine its ideology. Instead, we simply observe the ADA scores of the members of Congress who cite the think tank. This feature is important, since an active controversy exists whether, e.g., the Brookings Institution or the RAND Corporation is moderate, left-wing, or right-wing.
Previous Studies of Media Bias
One of the most curious and surprising statistics in all of American politics is that an overwhelming number of journalists are liberal. For instance, Elaine Povich (1996) reports that only seven percent of all Washington correspondents voted for George Bush in 1992, compared to 37 percent of the American public.1 Lichter, Rothman and Lichter, (1986) and Weaver and Wilhoit (1996) report similar findings for earlier elections.
The reason this statistic is curious and surprising is that many consider the media the watchdog of government, sometimes calling it the “Fourth Branch of American Government.” If so, it is by far the least representative of the branches. These statistics suggest that journalists, as a group, are more liberal than almost any congressional district in the country. For instance, in the Ninth California district, which includes Berkeley, twelve percent voted for Bush, nearly double the rate of journalists. In the Eighth Massachusetts district, which includes Cambridge, nineteen percent voted for Bush, more than triple the rate of journalists. In the 14th California district, which includes Palo Alto, 26 percent voted for Bush, more than four times the rate of journalists.
It is interesting to compare the unrepresentative nature of the media to the purported unrepresentative nature of the U.S. Senate. Some have noted that the U.S. Senate is unrepresentative of voters because small states are overrepresented. Further, since small states in the U.S. tend to be more conservative than large states, this causes a conservative bias in the Senate. However, even if the entire U.S. Senate were chosen only by voters from Mississippi, the most conservative state in the union in 1992 (50 percent voted for Bush), such an electorate would still be significantly more representative than the Fourth Branch of Government.2
Of course, however, just because a journalist has liberal or conservative views, this does not mean that his or her reporting will be slanted. For instance, as Kathleen Hall Jamieson (2000, 188) notes,
One might hypothesize instead that reporters respond to the cues of those who pay their salaries and mask their own ideological dispositions. Another explanation would hold that norms of journalism, including `objectivity’ and `balance’ blunt whatever biases exist.”
Or, as Timothy Crouse explains:
It is an unwritten law of current political journalism that conservative Republican Presidential candidates usually receive gentler treatment from the press than do liberal Democrats. Since most reporters are moderate or liberal Democrats themselves, they try to offset their natural biases by going out of their way to be fair to conservatives. No candidate ever had a more considerate press corps than Barry Goldwater in 1964, and four years later the campaign press gave every possible break to Richard Nixon. Reporters sense a social barrier between themselves and most conservative candidates; their relations are formal and meticulously polite. But reporters tend to loosen up around liberal candidates and campaign staffs; since they share the same ideology, they can joke with the staffers, even needle them, without being branded the “enemy.” If a reporter has been trained in the traditional, “objective” school of journalism, this ideological and social closeness to the candidate and the staff makes him feel guilty; he begins to compensate; the more he likes and agrees with the candidate personally, the harder he judges him professionally. Like a coach sizing up his own son in spring tryouts, the reporter becomes doubly severe. (1973, 355-6)
However, a strong form of the view that reporters offset or blunt their own ideological biases leads to a counterfactual implication. Suppose it is true that all reporters report objectively and their ideological views do not color their reporting. If so, then all news would have the same slant. Yet, few would disagree that Fox News or the Washington Times has a more conservative slant the New York Times.
A large number of economic studies give theoretical reasons that bolster the view that the media does not have a systematic bias. (See xx, xx, xx and xx). The idea is that if there were a systematic bias, then an entrepreneur could form a new media outlet that does not have a bias. This outlet would drive the others out of business. This is a compelling argument, and even the libertarian Cato Journal has published an article agreeing with the view: In this article, the author, Daniel Sutter (2001), concludes that, although it might be possible for a systematic bias to exist in the network news (since, before cable television, there were strong barriers to entry in this industry), such a bias is impossible, or at least very unlikely, for the newspaper, radio, or magazine industry.
However, contrary to the views and evidence cited above, we find a significant liberal bias in our sample of media outlets. This presents a challenge to economic theorists. Given that there is a systematic liberal bias the news market, at least one of the assumptions in the above theoretical studies must be inaccurate....
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