Polling problems

Michael Abramowitz:

Sen. John McCain and his allies say that they are. The country, they say, could be headed to a 2008 version of the famous 1948 upset election, with McCain in the role of Harry S. Truman and Sen. Barack Obama as Thomas E. Dewey, lulled into overconfidence by inaccurate polls.

"We believe it is a very close race, and something that is frankly very winnable," Sarah Simmons, director of strategy for the McCain campaign, said yesterday.

Few analysts outside the McCain campaign appear to share this view. And pollsters this time around will not make the mistake that the Gallup organization made 60 years ago -- ending their polling more than a week before the election and missing a last-minute surge in support for Truman. Every day brings dozens of new state and national presidential polls, a trend that is expected to continue up to Election Day.

Still, there appears to be an undercurrent of worry among some polling professionals and academics. One reason is the wide variation in Obama leads: Just yesterday, an array of polls showed the Democrat leading by as little as two points and as much as 15 points. The latest Washington Post-ABC News tracking poll showed the race holding steady, with Obama enjoying a lead of 52 percent to 45 percent among likely voters.

Some in the McCain camp also argue that the polls showing the largest leads for Obama mistakenly assume that turnout among young voters and African Americans will be disproportionately high. The campaign is banking on a good turnout among GOP partisans, whom McCain officials say they are working hard to attract to the polls.

... For instance, is the sizable cohort of people who don't respond to pollsters more Republican-leaning this year, perhaps because they don't want to admit to a pollster that they are not supporting the "voguish" Obama?

If so, that could mean the polls are routinely understating McCain's support. "I have no evidence that this is happening," Schier said, but he added: "I'm still thinking there's a 25 percent chance that this is a squeaker race and McCain pulls it out."

Other experts are less uncertain. Ruy Teixeira, a political demographer at the Center for American Progress and the Century Foundation, said averaging the daily polls points to "pretty much the same thing -- that the race is pretty stable and that Obama has a stable lead. Typically, when you are this far ahead at this point, it's hard to lose."

...

Averaging inaccurate data does not make it more accurate.

If the polls are off this year the likely cause is that most of the polls are using a much smaller sample of Republicans. This tends to skew the results in favor of Obama.

The Republicans best hope is found in those polls that show Obama below 50 percent and with a large number of undecideds. If those polls are accurate, McCain has a strong chance because the undecideds are likely to break against Obama.