In the end, after all the unskewing, the re-weighting and the hand-wringing, the polls were right — for the most part.
For months, pundits and pollsters debated whether public surveys were capturing accurate snapshots of the coming electorate, with conservatives in many cases alleging that polls were sampling too many Democrats and providing an artificial boost to Democratic candidates. These polls, and the averages and statistical models based on them, such as Real Clear Politics, Pollster.com, and The New York Times's blog FiveThirtyEight, drove the spurious narrative that President Obama held a significant advantage in the states most likely to decide the White House race, they argued.
Those critics were wrong, as Tuesday night showed, and the polls were correct: Obama did have that advantage, and it has propelled him to a second term. But the election also showed the polling industry is still facing increasing challenges related to how the various polls are conducted. The demographics of the country are changing, and the way in which Americans communicate with one another is changing even faster; both of these movements are significant threats to the future of telephone polling, whether conducted by live interviewers or automated computers.
Both live-caller and automated robo-polling methodologies had their share of hits and misses at the national and state levels. Nationally, polls from ABC News/Washington Post, NBC News/Wall Street Journal, and Pew Research Center performed well, while Gallup and the automated pollster Rasmussen Reports missed the mark, mostly showing Romney leading by various margins over the final few weeks of the campaign. The latter two are so prolific that Democratic groups commissioned their own set of polls late in the campaign to provide a counterweight to their results.
At the state level, some polls again performed fairly well, while others were less predictive. Overall, in many swing states, while Obama led in the averages produced by websites like Real Clear Politics and The Huffington Post's Pollster, he outperformed those averages.
"If anything, the polls understated" Obama's margin of victory, said Mark Blumenthal, the cofounder and editor of Pollster.
Blumenthal, speaking on Thursday at an event at the National Press Club, added that automated pollsters like Rasmussen Reports and the recently emerged, Florida-based firm Gravis Marketing were "the reason that those estimates" were too pessimistic for Obama. Those firms produced polls that consistently showed Obama underpeforming relative to other polls and the final election results. For example, Rasmussen's final polls showed Obama trailing by 3 percentage points in Colorado, 2 points in Florida and Virginia, and 1 point in Iowa. In Ohio and Wisconsin, the final Rasmussen polls showed Obama tied with Mitt Romney.
In most cases, these automated polls call only landline phones, though some firms, such as Rasmussen, augment their polls with self-selected Internet panels of respondents who only own cell phones as a means of incorporating the more than a third of Americans who are cell-only. The cell-only population tends to be younger, less white and is more likely to rent rather than own their homes, compared to the overall population. Automated polls do not meet National Journal's standards for publication, partly because of the cell phone issue.
As a result of their methodology, automated polls often miss younger, more racially diverse voters; that is particularly true of automated polls conducted in a single day, like those from Rasmussen. Their respondents are disproportionately older and whiter. But turnout did not drop among younger voters as some pollsters had predicted, according to exit polls. And the percentage of the electorate that was white continued to drop, to just 72 percent.
Asked by Slate about why his polls showed a closer race, if not a slight Romney advantage, Scott Rasmussen cited these two factors. "The two differences I noted were share of white vote falling to 72 percent," Rasmussen told Slate. "Also, youth turnout higher and senior turnout lower than expected."
The same phenomenon appeared to develop among some live-caller pollsters, both Republican and nonpartisan. For example, the independent firm Mason-Dixon Polling & Research produced two polls for Florida's two biggest newspapers over the campaign's final month that showed Romney ahead by 7 points and 6 points, respectively. The Miami Herald published a story on Wednesday acknowledging that these polls undersampled young and Hispanic voters.
These polls may have underestimated turnout among these groups because they were less likely to pass through the pollsters' likely-voter screens — batteries of questions that measure respondents' self-reported intention to vote, the attention they are paying to the campaign, their enthusiasm about voting, their voting history and other qualities typically predictive of behavior on Election Day.