Endorsements matter but voters are wise to media bias

The researchers take into account that newspapers are potentially biased in favor of one of the candidates and found that voters rationally account for the credibility of any endorsement. Endorsements for the Democratic candidate from left-leaning newspapers are less influential than endorsements from neutral or right-leaning newspapers and likewise for endorsements from papers sympathetic to Republican candidates. Knight said these results "suggest that voters are sophisticated and attempt to filter out any bias in media coverage of politics."

To estimate the influence of newspaper endorsements, the researchers used individual-level data on voting intentions and newspaper readership in the months leading up to the 2000 and 2004 elections. They measured endorsement credibility based on the ideological leanings of newspapers, ownership, and reader preferences.

To provide a sense of the magnitude of endorsement effects, Knight and Chiang feature a data table that shows the estimated influence in the top 20 newspapers during the 2000 presidential campaign. They show the least credible endorsements were for Al Gore from The New York Times and for George W. Bush from the Dallas Morning News, which convinced less than 1 percent of their readers to switch allegiance to the endorsed candidate. By contrast, the endorsement with the largest effects came from the Chicago Sun Times and the Denver Post, both of which had surprising endorsements. The Chicago Sun Times was predicted to endorse Gore with a probability of 58 percent, but instead endorsed Bush, while the Denver Post endorsed Gore even though it was only predicted to do so by a probability of only 35 percent. Both "surprising" endorsements convinced about 3 percent of readers to switch allegiances, according to the findings. Knight and Chiang also found that endorsements are more influential among moderate voters.

Provided by Brown University