Asking for a polling post-mortem at this stage is a little bit like asking a coroner for the cause of death while the body is still at the crime scene. You’re going to have to wait to conduct a full autopsy.
But make no mistake: It’s not too early to say that the polls’ systematic understatement of President Trump’s support was very similar to the polling misfire of four years ago, and might have exceeded it.
For now, there is no easy excuse. After 2016, pollsters arrived at plausible explanations for why surveys had systematically underestimated Mr. Trump in the battleground states. One was that state polls didn’t properly weight respondents without a college degree. Another was that there were factors beyond the scope of polling, like the large number of undecided voters who appeared to break sharply to Mr. Trump in the final stretch.
This year, there seemed to be less cause for concern: In 2020, most state polls weighted by education, and there were far fewer undecided voters.
But in the end, the polling error in states was virtually identical to the miss from 2016, despite the steps taken to fix things. The Upshot’s handy “If the polls were as wrong as they were in 2016” chart turned out to be more useful than expected, and it nailed Joe Biden’s one-point-or-less leads in Pennsylvania, Georgia and Arizona.
