Partisan Bias, Political Information and Spatial Voting in the 2008 Presidential Election

This article provides direct estimates of the parameters of spatial utility models of voting using data from the 2008 presidential election. By measuring citizens’ views on issues for which candidates’ stances are known, I estimate voter ideology on the same scale as candidate positions. Using these estimates, I demonstrate that policy exerts a strong influence on vote choice for most voters. While independents appear to cast their ballots in accordance with the assumptions of unbiased spatial voting, partisans are strongly biased toward their party’s nominee by spatial standards. At lower levels of political information, voters are influenced primarily by their party identification, with policy views having little impact on vote choice. More highly informed citizens, by contrast, show strong relationships between policy views and vote choice. As information levels increase, the spatial biases exhibited by partisan voters decreases, but even among the most informed citizens, significant partisan biases remain.