Sunday, September 14, 2008

When is a bounce not a bounce?

WE'VE MOVED! Democratic Convention Watch is now at

That's really the big question right now. McCain has gotten a bounce from his convention and his VP pick. (She who shall not be named). But will it last?

The graph at left, from FiveThirtyEight, shows that a convention bounce peaks 7 days after the convention, and takes another 21 days to dissipate. We're only 10 days after the convention, and there are already some small signs in the tracking polls that the bounce is starting to weaken.

And with the back-to-back conventions, and the debates in 12 days, is this year typical or atypical? Well, with elections only once every 4 years, is any election typical? CQ looks at some past elections:

  • 1960: Nixon got a small bounce, but it was gone by the first debate.
  • 2000: Gore got a big 10 point bounce, Bush had an 11 point lead after the debates, and Gore ended up winning the popular vote.
  • 1988: Bush maintained and built on his convention bounce.
  • 1976: Carter has a 33 point lead after his convention, Ford cut it in half after his convention, and kept going, closing to a 2 point gap on election day.
So what do we take from all this? Here's Andrew Kohut, the president of the Pew Research Center:

Post-convention bounces tend to be "transitory," Kohut said. There is "more fluidity in public opinion during convention periods" than at other times, he said, and he prefers to wait until they can conduct a survey with a "more stable shelf life." While the tracking polls provide a "nice record of immediate reactions," Kohut said, observers are still left asking, "where will they be next week?" - National Journal Online
I think "next week" is this week. If Obama can retake the lead in the tracking polls, which he is very close to doing, and in the composite (McCain now leads, 46.9-44.8), I think he can move on to the debates in the same environment he was pre-convention - with a small but clear lead in the popular vote and EV count. We'll be following the polls all week.