There is one nightmare that must make Democratic election operatives wake up in cold sweats: much of the presidential polling was wrong in 2016 and again in 2020. Some of the biggest polls overstated Democratic support in both elections.
How and why this happened — and how to adjust for it in polling — is still somewhat of a mystery.
The New York Times debuts a newsletter today called The Tilt by Nate Cohn. (Sign up here.) Cohn examines in the inaugural edition of the newsletter these vexing questions.
Ahead of the last presidential election, we created a website tracking the latest polls — internally, we called it a “polling diary.” Despite a tough polling cycle, one feature proved to be particularly helpful: a table showing what would happen if the 2020 polls were as “wrong” as they were in 2016, when pollsters systematically underestimated Donald J. Trump’s strength against Hillary Clinton.
The table proved eerily prescient. Here’s what it looked like on Election Day in 2020, plus a new column with the final result. As you can see, the final results were a lot like the poll estimates “with 2016-like poll error.”
We created this poll error table for a reason: Early in the 2020 cycle, we noticed that Joe Biden seemed to be outperforming Mrs. Clinton in the same places where the polls overestimated her four years earlier. That pattern didn’t necessarily mean the polls would be wrong — it could have just reflected Mr. Biden’s promised strength among white working-class voters, for instance — but it was a warning sign.
That warning sign is flashing again: Democratic Senate candidates are outrunning expectations in the same places where the polls overestimated Mr. Biden in 2020 and Mrs. Clinton in 2016.
Cohn goes on to note:
The pattern of Democratic strength isn’t the only sign that the polls might still be off in similar ways. Since the Supreme Court’s Dobbs decision on abortion, some pollsters have said they’re seeing the familiar signs of nonresponse bias — when people who don’t respond to a poll are meaningfully different from those who participate — creeping back into their surveys.
Brian Stryker, a partner at Impact Research (Mr. Biden is a client), told me that his polling firm was getting “a ton of Democratic responses” in recent surveys, especially in “the familiar places” where the polls have erred in recent cycles.
None of this means the polls are destined to be as wrong as they were in 2020. Some of the polling challenges in 2020 might have since subsided, such as the greater likelihood that liberals were at home (and thus more likely to take polls) during the pandemic. And historically, it has been hard to anticipate polling error simply by looking at the error from the previous cycle. For example, the polls in 2018 weren’t so bad.
Some pollsters are making efforts to deal with the challenge. Mr. Stryker said his firm was “restricting the number of Democratic primary voters, early voters and other super-engaged Democrats” in their surveys. The New York Times/Siena College polls take similar steps.
My biggest fear is that the overstating of Democratic support will depress turnout among progressive voters. These polling mistakes only prove that, no matter how much you think Democrats are ahead, all of us need to get out and vote every time.