Sunday, September 14, 2008

When is a bounce not a bounce?

WE'VE MOVED! Democratic Convention Watch is now at http://www.DemocraticConventionWatch.com

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 pollster.com 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.

Comments (8)

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Its not rocket science, all Obama has to do is show how Mccain is not the Common man, especially if he can connect his historical economic views to the failing housing market. Palin and waffles and lipstick
is a distraction because McCain has little substance
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Today really is a key day in the polls. The Rasmussen tracking poll had a weird blip up by three points three days ago, suggesting a very good night of polling for McCain. There wasn't anything in particular that would justify a sudden jump like that, so it was probably just a fluke. Since Rasmussen tracking averages three days of result, it should cycle out of their average today.

There's also a little evidence that the bounce has peaked. Put those two together, and the Rasmussen tracking poll could jump from McCain + 3 to Obama +1 today. If that happens, people who watch every blip will go crazy, thinking that Palin's interview , or maybe the lipstick flap, has burst the Palin bubble.

It's not true, of course. It's fluky data from three days ago going away, plus a slow loss of the bounce.

BUT perception has a funny way of becoming reality. Once people think the Palin phenom is getting stale, more supporters will peel off. Don't get me wrong--there are a lot of social conservatives who love her, and would follow her off a cliff. McCain's enthusiasm numbers will never return to where they were before the pick. But we may see a change in the narrative in the next day or two.

On the other hand, a day of bad luck with Ramussen tracking might mean it "only" drops to McCain + 1. Keep your fingers crossed...
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2 replies · active less than 1 minute ago
So much for that theory. Rasmussen tracking has McCain +2.

Hmm...thinking, thinking.

Rasmussen occasionally rejiggers their weighting to account for party ID. I bet that after the Republican convention, more people identified themselves as Republicans, and they started reweighting based on that three days ago. So what I thought was a weird day was actually an artifact of their polling method. (No, I'm not accusing them of trying to bias the numbers; it's just the way their method works.) So no sudden drop, just the gradual erosion of the bounce we've seen in other polls.
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You would win that bet: http://www.rasmussenreports.com/public_content/po...

For polling data released during the week of September 14-20, 2008, the new targets are 38.7% Democratic, 33.6% Republican, and 27.7% unaffiliated. For the first thirteen days of September, the targets were 39.7% Democrat, 32.1% Republican, and 28.2% unaffiliated. It should be noted that these figures indicate an improvement for Democrats since the beginning of the year.

The new targets are fairly similar to the ratio that existed when Democrats won control of Congress in 2006. They are also fairly close to the make-up of the electorate in the Presidential elections of 2000 and 1996.
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uplandpoet's avatar

uplandpoet · 864 weeks ago

Matt, I want to post a new thread, but not sure what your rules are. could you contact me at awatkins@bellsouth.net?
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I'm waiting for the ONE USAToday/Gallup poll of McC +10 to roll off or the realclearpolitics rolling average. Since the next highest number if McC+4, and it drops of rapidly after that to McC +2 (and some Obama positives and ties), the rolling avg at RCP should drop from McC+2 to McC +1. Hopefully today.

and then even more by the end of the week. I don't think the McC bounce was EVER as high as +2.5 or whatever, since that +10 looks to my eyes to be an outlier.
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oh, and ANOTHER thing: when you compare the two bounces, the Obama bounce ranged from Obama +6 to +9 across several polls. When you look at the McC bounce (discounting that ONE +10) it ranged from +1 to +4.

devil is in the details, no?
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538's consolidated bounce (trying to figure out the effect of putting the two bounce effects on top of each other with the one-week gap) puts the peak of the McCain bounce as this week with it starting to decline about Thursday and being cycled out just before the first debate. By their calculations, McCain is currently about 2% higher than he will be next Thursday.
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