The first of three presidential debates is set for one week from today at the University of Denver (a fourth debate is scheduled between the vice presidential candidates). As we reported in last week’s Friday Roundup, the first debate will focus largely on the economy, with three of the six fifteen-minute segments dedicated to the economy, while the other three will focus on "health care," "the role of government," and "governing.” Will these debates really matter for the outcome in November? Probably not. But, at least a third of American households will tune in to root on their candidate.
As it happens, I’ve been reading a terrific new book just released this month – The Timeline of Presidential Elections by Robert S. Erikson and Christopher Wlezien – that delves into the elements of the presidential campaign timeline that matter for changing preferences in the aggregate vote. Using aggregate polling data, the authors document that voter intentions do change over the course of presidential campaigns. However, voter preferences are more volatile in some election years than others. Not surprisingly, party conventions play a major role in shuffling the electorate's vote choices and it is around convention time that voter preferences are the most volatile. Conventions thus do a good job of getting voter’s attention sufficiently enough to change minds. But preferences harden nearly every year following the party conventions, with fewer voters changing their minds in the fall general campaign season.
Following the conventions, the next big campaign event is usually the presidential debates. Unlike conventions, however, numerous political scientists have shown that the presidential debates do not matter and do not change voter preferences. Detailed studies of individual debates show that, at most, polls swing only one to three points in some of the more salient debates where one of the candidates out-performs the other, such as the 1980 debate between Jimmy Carter and Ronald Reagan (two points for Reagan, who was already in the lead); the 1988 debate between George H.W. Bush and Michael Dukakis (one point to Bush, who was already in the lead); the 1992 debate between Bush and Bill Clinton (probably cost Bush two points); and Al Gore’s endless signing in the debate with George W. Bush (about two to three points to Bush). Of these, the only debate that could have been consequential to the election outcome was the Gore v. Bush debate.