11.25.2019 08:45 AM

How the pollsters got Trump’s victory wrong

Fascinating piece in the Times. Key reasons they messed up:

  • they didn’t weight for education
  • they underestimated intensely anti-Obama voters
  • they missed the “shy Trump” supporters

Excerpt:

By and large, nationwide surveys were relatively accurate in predicting the popular vote, which Hillary Clinton won by two percentage points. But in crucial parts of the country, especially in the Midwest, individual state polls persistently underestimated Mr. Trump’s support. And election forecasters used those polls in Electoral College projections that gave the impression Mrs. Clinton was a heavy favorite.

AAPOR’s analysis found several reasons the state polls missed the mark. Certain groups were underrepresented in poll after poll, particularly less educated white voters and those in counties that had voted decisively against President Barack Obama in 2012. Respondents’ unwillingness to speak honestly about their support for Mr. Trump may have also been a factor.

These and other issues could reappear in 2020, pollsters warn, if they’re not addressed directly.

To make sure their results reflect the true makeup of the population, pollsters typically “weight” their data, adding emphasis to certain respondents so that a group that was underrepresented in the random sample still has enough influence over the poll’s final result. Polls typically weight by age, race and other demographic categories.

But some state-level polls in 2016 did not weight by education levels, therefore giving short shrift to less educated voters, who tend to be harder to reach.

This often understated Mr. Trump’s support, since he was markedly more popular than past Republican nominees among less educated voters — and noticeably less popular among those with higher degrees, who research suggests are more likely to participate in polls.

The AAPOR analysts found that many polls in swing states would have achieved significantly different results had they been weighted for education. This, in turn, would have noticeably decreased Mrs. Clinton’s lead in much-watched polling averages and forecasts of these states.

6 Comments

  1. You need to fix the link.

    Here is a 538 podcast episode with Nate Silver and Nate Cohen that discusses this https://fivethirtyeight.com/features/politics-podcast-could-trump-lose-the-popular-vote-and-win-again/ (I haven’t finished listening to it.)

  2. Des says:

    I read that Bloomberg’s campaign manager was on MSNBC today (I don’t watch MSNBC personally) and said that Trump wins the next election if held tomorrow. He says that as of today Michigan, Wisconsin, Pennsylvania, and Florida are still in Trump’s camp. I don’t think he’s wrong either. If Warren takes the nomination, I think Trump wins big.

    • Des,

      Lucky for Trump, the recession is probably coming before Americans vote!

    • The Doctor says:

      What you say about those states you list does not square with the current Morning Consult polling numbers for those states. The only one of those states that has Trump ahead or tied is Florida, and that’s by a hair. He’s behind in all the others in favourability ratings.

      I’m not saying Trump will lose in 2020, just pointing out facts as they exist now.

      • Gord Tulk says:

        Those favourability ratings are based on a Generic dem candidate.

        When you look at polling that puts Trump head-to-head against named dem candidates you get very different results:

        for example:

        https://projects.fivethirtyeight.com/polls/wisconsin/

        Thus what Bloomberg says is true. Trump basically cleans the clock of any of the top four candidates on the dem side in those “swing states”(very notable that MB does not include Ohio as a swing state any more).

        And that is what is freaking out the establishment Dems.

        • The Doctor says:

          Gord, thanks for the information — I wasn’t aware that 538 had state matchups like that. I note that of the other “swingers”, the Pennsylvania results have the Dems winning, and Michigan and Ohio are mixed.

          I still see 2020 as a bit of a toss-up. There are lots of headwinds facing Trump, but the economy and (especially) the makeup of the electoral college are his two strongest suits. And there’s no Messiah on the horizon in terms of a Democratic nominee.

          There almost certainly will be a continual drip drip drip of negative information regarding Trump, so there is a big unpredictable variable there. A lot of people have tuned much of that out, but I could see Trump scoring some massive own goal, because he’s so profoundly personality disordered and delusional. E.g., an even stupider, more deranged phone rant to Fox & Friends than his last one, or better yet, actually agreeing to give live testimony under oath (hey, Bill Clinton did, why not Trump?).

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