National and statewide polls show former Vice President Joe Biden leading President Donald Trump ahead of Tuesday’s election.
In Wisconsin, FiveThirtyEight’s polling averages have Biden ahead by about eight points. In Pennsylvania, about five points, and in Florida, two.
But polls are by no means definitive indicators of victory or defeat. In 2016, many favored Hillary Clinton to win the presidency — but that went to Donald Trump.
“In 2016, the error for national polls was fairly low. The challenges in 2016 were a lot of undecided voting that broke for Trump disproportionately, and a bit more polling error in some of the upper Midwest state polls,” said David Dutwin, senior vice president of strategic initiatives at NORC at the University of Chicago, a nonpartisan research institute. “It’s tough, when polling accurately predicts the popular vote but does not predict the winner, the narrative after that was that the polling got it wrong. But again, it was quick, accurate and did predict the popular vote.”
Pollsters have pointed to adjustments made this election cycle they say will help them more accurately poll voters, especially in battleground states both Biden and Trump need in order to win the Electoral College. That includes weighting polls for education level.
“So not using the statistical tool of weighting, and weighting to education back in 2016, really had a negative impact on the polling, because you were missing this whole demographic that propelled Trump to victory,” said Ashley Koning, director of the Eagleton Center for Public Interest Polling at Rutgers University. “Not accounting for enough non-college educated individuals and respondents was a pretty painful impact to a lot of polling, especially in close races.”
Another ongoing challenge for pollsters has been low response rates, which Koning says have dropped since 2016. But she says that doesn’t automatically translate to a less accurate sample of a population.
“We don’t necessarily see a correlation between response rate and response bias in the surveys that we’re doing … we do still see that polls are representative of the population whether or not [a lot of] respondents are answering or not,” she said.
As of Monday evening, almost 100 million Americans had already cast their ballots, either in person or by mail.
Koning says that means polling is harder and more complex, but still valuable.
“We know from the numbers so far with early voting and mail-in ballots, they’re leaving heavily Democratic. If we didn’t have polls, we would be focusing on an electorate that’s heavily Democratic and most likely voting for Biden, instead of knowing the bigger picture,” she said.
Amid all the extra challenges facing voters in 2020, Dutwin says he still has faith in the utility of election polling.
“A lot of things can happen this election cycle, with mail-in balloting and all the different things, the pandemic and different ways that this is a very unique election cycle. It’s hard to say how far the actual vote will travel from polls, but I think we should we should expect that polling will continue to be as accurate as it’s been historically,” Dutwin said.