The Asterisk on Kamala Harris's Poll Numbers
Pollsters think they've learned from their mistakes in 2020. Of course, they thought that last time too.
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The 2016 election lives in popular memory as perhaps the most infamous polling miss of all time, but 2020 was quietly even worse. The polls four years ago badly underestimated Trump's support even as they correctly forecast a Joe Biden win. A comprehensive postmortem by the American Association for Public Opinion Research concluded that 2020 polls were the least accurate in decades, overstating Biden's advantage by an average of 3.9 percentage points nationally and 4.3 percentage points at the state level over the final two weeks of the election. (In 2016, by contrast, national polling predicted Hillary Clinton's popular-vote margin quite accurately.) According to The New York Times, Biden led by 10 points in Wisconsin but won it by less than 1 point; he led Michigan by 8 and won by 3; he led in Pennsylvania by 5 and won by about 1. As of this writing, Harris is up in all three states, but by less than Biden was. A 2020-size error would mean that she's actually downand poised to lose the Electoral College.
The pollsters know they messed up in 2020. They are cautiously optimistic that they've learned from their mistakes. Of course, they thought that last time too.
How did the polls get worse from 2016 to 2020, with everyone watching? In the aftermath of Trump's surprise 2016 victory, the public-opinion-research industry concluded that the problem was educational polarization. If pollsters had made a point of including enough white people without college degrees in their samples, they wouldn't have underestimated Trump so badly. During the 2020 cycle, they focused on correcting that mistake.
It didn't work. Even though polls in 2020 included more white non-college-educated voters, they turned out to be disproportionately the white non-college-educated voters who preferred Biden. The new consensus is that Republican voters are less likely to respond to polls in the first place, even controlling for education level. (To put it more nerdily, partisan preference correlates independently with willingness to take a poll, at least when Trump is on the ballot.) Don Levy, the director of the Siena College Research Institute, which conducts polls on behalf of The New York Times, calls the phenomenon "anti-establishment response bias." The more someone distrusts mainstream institutions, including the media and pollsters, the more likely they are to vote for Trump.
