Will the debates matter?

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Tom Holbrook, who had an excellent analysis of convention bounces, turns his attention to debates, trying to answer the question: Do the debates make any difference?

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.

But how about a series of debates?

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. Of these, the 2000 debates stand out as the most important, especially in the context of the closeness of the election.

So we could see a small shift. And even a shift of 2 points could mean the difference between a nail-biter and a 100 Electoral Vote Obama victory.