This Friday night John McCain and Barack Obama meet in the first presidential general election debate in Oxford, Mississippi. The subject: national security. The stakes are high for both camps–or are they? Political scientist Tom Holbrook argues that despite all the emphasis on the debates, these events move the numbers less than many might think. Analyzing movement in national polls following debates in the past five presidential elections (1988-2004), he writes:
These data suggest that the norm is for very little swing in candidate support following debates. Across all thirteen presidential debates the average absolute change in candidate support was 1 percentage point. There are a few notable exceptions, of course. Two that stand out are the second debate in 1992, following which George H.W. Bush lost 2 points, and first debate of 2004, after which George W. bush lost 2.26 points. Other debates with above average (but still small) vote shifts are the first debate in 1996 and the second debates in 1988 and 2000.
However, Holbrook also notes the “cumulative” effect of all three debates might produce more movement in the polls. Focusing on single debate bumps may be obscuring a more general, cumulative effect of debates. The last column in the table
shows the change in candidate support from one week prior to the first debate to one week after the final debate. Here we see that the debate period generated a 2.42 point bump for George H. W. Bush in 1988, cost Al Gore 3.52 points in 2000, and cost George W. Bush almost 2 points in 2000
Bottom line according to Holbrook:
I don’t expect to see large swings in candidate support following the individual debates, barring something really spectacular happening. However, even relatively small shifts in the same direction over the three debates could make this relatively tight race even tighter (if the shifts favor McCain), or could blow it open (if the shifts favor Obama).
I don’t care; I’m still watching! Read Holbrook’s entire post here.
