07/28/2008 01:27 pm ET Updated Dec 06, 2017

Berlin Bounce?

The polling question of the morning seems to be whether Barack Obama has experienced a "Berlin bump" in his poll numbers in the wake of the weeklong trip to Europe and the Middle East. Yesterday's Washington Post featured Barack Obama himself downplaying the possibility: "I don't think that we'll see a bump in the polls. I think we might even lose some points. People back home are worried about gas prices; they're worried about jobs."

But by mid-afternoon, however, the latest release of the Gallup Daily survey, conducted Thursday through Saturday, showed Obama's margin increasing to 9 percentage points (49% to 40%), "the largest," wrote Gallup's Frank Newport, "since Gallup began tracking the general election horserace in March." That news was enough to merit the full Drudge treatment yesterday and a screaming headline on the front page of the New York Daily News.

The Rasmussen Daily tracking also showed Obama expanding his lead slightly, from dead even (46% to 46%) early in the week to an advantage that was five points on Saturday (49% to 43%) and three points today (48% to 45%).

But is this apparent "bump" real? Will it last? And is the vote preference question really the best place to look for the bump?

Put me down as in general agreement with our friends at First Read about the danger of over-analyzing one particular poll. Here are a few reasons for skepticism:

First, even Gallup's Newport hedged: "A key question remains as to whether this "bounce" is short-term (as happens to bounces in some instances following intense publicity surrounding a convention) or if his lead will persist."

It is true that some events produce a temporary "bounce" that rarely persists, especially if the coverage is uniformly good for one candidate and not so good for another (as seems to have been the case for the last few days). One possibility to consider is that surveys with short field periods might have some bias toward those who happened to be at home viewing that positive coverage.

Second, while Obama's lead on the Gallup Daily was bigger than they have shown previously, it is only slightly bigger. Since Hillary Clinton endorsed him in early June, but before last week, Obama had led on the Gallup Daily by 7 points (once) and 6 percent (five times). And Gallup's data continues to show Obama doing very slightly better on weekends (but perhaps not significantly -- more on this issue later this week).

Third, and most important, if the volatility is about voter preferences and not poll methodology, it reflects the fact that (as David Moore has been reminding us) as many as a third of registered voters are willing to say they are less than certain about their choice. This hesitance is not unusual. Contrary to what Robert Novak implies in his column today, candidates rarely "close the deal" with uncertain voters in July, especially when they are non-incumbents and relative newcomers.

First Read recommends that we "wait a bit until the next few national polls are released before declaring whether Obama got a bounce from his overseas trip." That's good advice.

And while we are at it, we might want to focus more closely on the sorts of internal measures that might have seen some improvement. Has Obama improved at all on probes of his readiness for the job, particularly on questions that ask for evaluations of Obama alone, rather than posing a choice between Obama and McCain? That is the best test of what sort of "bounce" Obama gets out of last week's trip.

Update: Today"s Gallup Daily, released just minutes before I clicked "publish," shows Obama leading by eight points (48% to 40%).

Update 2: "And then," as Michael McDonald puts it below, "there's this." The latest USA Today/Gallup poll -- an entirely separate survey from the Gallup Daily -- puts Obama ahead by just three points (47% to 44%) among 900 registered voters, but behind McCain by four points (45% to 49%) among the 791 considered most likely to vote.

All of this should make us more cautious about reading too much into the fluctuations between these surveys and about assuming too much about the precision of these sorts of measurements when take over a July weekend.

There are really two stories here: The first is about why the Gallup Daily survey of registered voters conducted Friday through Sunday shows Obama leading McCain 48% to 40%, while the USA TodayGallup poll of registered voters conducted over the same three days shows Obama leading 47% to 43%. It could have something to do with the order of questions, with the special difficulty of interviewing over a weekend or, perhaps as Frank Newport suggests, random sampling error. The surveys are a point apart on Obama's vote and the three point difference in McCain's support is not quite large enough to be statistically significant, even with 2,674 respondents on the Gallup Daily (though it comes close).

The more difficult story, and one I will post on either later tonight or tomorrow, is about why McCain does so much better with "likely voters" than registered voters. Keep in mind that the ABC News/Washington Post survey conducted earlier this month showed a very similar effect. The editors at both organizations, who emphasized the registered voter numbers appear to agree with what Gallup's Frank Newport told Jill Lawrence of USA Today: "'[R]egistered voters are much more important at the moment,' because Election Day is still 100 days away."