By Robert J. Barro Many people think the mainstream media have a liberal bias. Media spokesmen, however, usually deny such claims. So who's right? Is there a left-wing bias, or has the right wing conspired not only to influence the media but also to create a false image of unfairness? Some scientific evidence is available in a continuing study, A Measure of Media Bias, by Tim Groseclose of the University of California at Los Angeles and Jeff Milyo of the University of Chicago, presented last March at Stanford University's Workshop on the Media & Economic Performance. These researchers set up an objective measure of bias in U.S. television networks, newspapers, and magazines. The main finding is that the liberal inclination is pronounced. Although Fox News emerges as conservative, it is not nearly as far to the right as many outlets are to the left.
Groseclose and Milyo began with the well-known ratings of the voting records of U.S. senators and representatives by Americans for Democratic Action (ADA), a self-described liberal lobbying group. The researchers used data for the 1990s and adjusted the ADA scores to make them comparable over time and across the two chambers. On a 0-100 scale, with 100 the most liberal, the median member of the U.S. House had an ADA score of 39. Thus, 39 is a reasonable measure of a centrist position. Among well-known senators, Bill Frist (R-Tenn.) had a highly conservative score of 4, whereas Edward M. Kennedy (D-Mass.) had a strikingly liberal score of 80.
THE NEXT STEP MEASURED the tendency of Senate and House members in their speeches to cite 200 prominent think tanks. The citations considered were those that referred favorably to a view or fact presented by a think tank. Not counted were negative citations or those purely descriptive of a think tank's actions. As an example, the Heritage Foundation was cited by legislators whose average ADA ratings were 6 -- that is, very conservative. Also highly conservative were the Family Research Council (rating of 6) and the National Right to Life Committee (7). Left-wing think tanks included the Center on Budget & Policy Priorities (80), the Children's Defense Fund (77), and the Economic Policy Institute (72). Surprisingly, the American Civil Liberties Union was centrist (35), an outcome driven by the ACLU's opposition to campaign-finance reform.
The last step measured the tendency of various media outlets to cite the same 200 think tanks. The researchers considered only "news stories" -- not editorials, letters to the editor, and so on. The periods covered ranged from 1990 to 2003. Again, the citations were those that referred favorably to a view or fact provided by a think tank. The researchers used this information to calculate a right- vs. left-wing indicator for each media outlet -- effectively, an ADA rating. The assumption is that media outlets that refer favorably to conservative think tanks are reasonably characterized as conservative, whereas those that refer positively to liberal think tanks are plausibly labeled as liberal. The final product (in a preliminary table provided by the authors) was a list of computed ADA ratings for the media outlets.
On the conservative end, Fox News Special Report came out with a rating of 27; that is, 12 points more conservative than the 39 of the median member of the House. The only other right-of-center outlet was The Washington Times, at 34.
On the liberal end, Newsweek had an astonishing rating of 72 -- that's 33 points more liberal than the House median. Other highly liberal outlets included The New York Times, Time magazine, the CBS Evening News, USA Today, and NBC Nightly News. These scores ranged from 62 to 64, about 25 points above the House median. For viewers seeking truly "fair and balanced" reporting, the best outlets were ABC Good Morning America and NewsHour with Jim Lehrer. The ADA scores for these programs were 39 and 41, respectively. Places moderately left of center were CNN's NewsNight with Aaron Brown (49), The Washington Post (53), NPR's Morning Edition (55) and ABC WorldNews Tonight (55).
Because of problems in data collection, the list excluded The Wall Street Journal, but it will be added soon. Also excluded is talk radio, which seems to have a conservative bent. Bottom line: The Groseclose-Milyo study shows the media are skewed substantially to the left of the typical member of Congress. Thus, if the opinions of viewers and readers are similar to those of their representatives, the media slant is far to the left of that of most of their customers.
Robert J. Barro is a professor of economics at Harvard University and a senior fellow of the Hoover Institution ( firstname.lastname@example.org)