Sen. Arlen Specter says people don't vote the way they poll. But mind you, he is a republican. Only two more days.
The Washington Post thinks the polling is right -- THINKS:
I don't consider any of these fatal or even very serious problems, but that doesn't mean I'm immune to pollster's paranoia. We could all be wrong -- at least theoretically.
Simply put, we may be wrong about who is likely to vote on Tuesday. One of the trickiest parts of political polling is determining which of the people interviewed in pre-election surveys will really vote. It's relatively easy for us to identify such sharply delineated groups as the population of all adults living in the United States or even all registered voters, but the pool of actual voters is a group that exists at a single point in time, on Election Day (plus those casting ballots early and by mail).
The upside:
These "likely voter models" vary widely from pollster to pollster. This year, the Gallup Organization is publishing two models. Its "traditional" model factors in respondents' reports of whether they voted in previous elections to determine who is a "likely" voter. But Gallup's new, "expanded" model drops this requirement, putting more young and minority voters into the "likely voter" category.
In Washington Post-ABC polling, we ask a series of questions about whether and how people plan to vote, whether they have voted before and basic knowledge about the voting process. We then feed all this information into a range of models, corresponding to different levels of turnout. We report a single model, but only after assessing the quality and impact of all of them. Likely voter modeling is a craft, bolstered by science.
I'm also often asked about the rising use of cellphones. The number of people ditching their home telephones has spiked in recent years, with the highest percentages among young adults and nonwhites. Does this affect the polls? Probably not -- or at least not yet. The exclusion of cellphone users appears to have no more than a minimal effect on the results. But even if these voters turn out to have been systematically underrepresented in this year's polls, that would actually mean that Obama had an even larger lead, because these voters overwhelmingly back him over McCain. And both the Gallup and Washington Post-ABC tracking polls interview complementary samples of voters who have only cellphones to make sure that we're not missing something. (Few state polls include cellphone interviews.)
Others who doubt this year's polls raise the question of a "Bradley effect." This syndrome gets its name from the bid by Tom Bradley, then the African American mayor of Los Angeles, to become governor of California in 1982. He headed into Election Day with a big seven-point lead in the last publicly released poll, only to lose narrowly. Some attributed this startling result to a quiet form of racism that revealed itself only in the voting booth, and the 1982 case has been trotted out ever since to cast doubt on the accuracy of pre-election polls in contests between white and black candidates.
But there is good reason to doubt that racism was the cause of Bradley's defeat, and decades of polling in other campaigns with black candidates should mute some of the skepticism. No "Bradley effect" has shown up for years, and a new analysis by one Harvard University researcher, Daniel Hopkins, shows that any such effect that existed in African American politicians' contests in the late 1980s and early 1990s has now disappeared.
