They don’t call it a horse-race for nothing.
But it becomes harder to ignore an outlier when it’s A) close to the election and B) one of the oldest and most respected polling outfits in the nation. Thus as the media enters Campaign 2012’s home stretch, the narrative of a nip-and-tuck contest looks decidedly jeopardized by Gallup showing Mitt Romney with a 7% lead – and such an outcome apparently has to be challenged:
With a record of correctly predicting all but three of the 19 presidential races stretching back to 1936, Gallup is one of the most prestigious names in the business and its outlier status has other polling experts scratching their heads.
“They’re just so out of kilter at the moment,” said Simon Jackman, a Stanford University political science professor and author of a book on polling. “Either they’re doing something really wacky or the other 18 pollsters out there are colluding, or something.”
The caveats to Gallup’s polling (as with any pollster) are well-versed. But to find an answer as to why Gallup posts a major Romney lead while the Real Clear Politics average of pollsters shows essentially a tie has nothing to do with credibility or collusion. It has everything to do with turnout.
Take the recent IBD/TIPP poll as Gallup’s doppleganger with Obama leading by 5.7%. Democrats are outsample Republicans by 7%. The UConn Courant showing Obama up 3%? The sample shows Democrats with an 8-point advantage. Gallup plays their cards close to the vest, not showing the partisan affiliation of their likely voter model. But their registered voter breakdown still shows a Romney lead, albeit of a modest 3% and is likely based on their party affiliation polls showing Democrats up 4 points.
Gallup says it determines its “likely voters” by asking whether they have voted in the past, if they know where their polling place is located, and other similar questions. The formula has been tweaked this year to take into account the increasing prevalence of early voting.
Gallup’s Newport pointed out that the firm’s likely-voter formula has more accurately predicted the election results than its wider poll of all registered voters going back to the 1990s and, in fact, the likely voter prediction tended to slightly favor Democratic candidates.
The idea of a single pollster being simply a part of a larger trendline is accurate, even if most media outlets tend to overlook that fact to trumpet their own poll to the exclusion of competitors and thus create news rather than report it. Yet even if we exclude Gallup’s results, the trendlines have to be concerning for Obama’s camp. Despite wielding turnout margins better than what propelled him into office four years ago, many polls show Barack Obama at best narrowly ahead – and more commonly tied or behind.
Gallup might be overstating Romney’s support, although the pollster’s worst estimations of support were in the 5-6 point range and happened in 1936 and 1948. In the modern era, if anything Gallup has consistently overestimated Democratic support at the polls, giving Obama 2% more, Kerry 0.7% more and Clinton 2.8% and 5.7% more in his campaigns. Which may mean that despite a 7% lead causing headaches among the media, Mitt Romney may…hold for dramatic effect…lead by more.