November 13, 2016

What polls aren’t good for

From Gallup, how Americans feel about the election

gallup

We can believe the broad messages that many people were surprised; that Trump supporters have positive feelings; that Clinton supporters have negative feelings; that there’s more anger and fear expressed that when Obama first was elected (though not than when he was re-elected). The surprising details are less reliable.

I’ve seen people making a lot of the 3% apparent “buyer’s remorse” among Trump voters, with one tweet I saw saying those votes would have been enough to swing the election. First of all, Clinton already has more votes that Trump, just distributed suboptimally, so even if these were Trump voters who had changed their minds it might not have made any difference to the result.  More importantly, though, Gallup has no way of knowing who the respondents voted for, or even if they voted at all.  The table is just based on what they said over the phone.

It could be that 3% of Trump voters regret it. It could also be that some Clinton voters or some non-voters claimed to have voted for Trump.  As we’ve seen in past examples even of high-quality social surveys, it’s very hard to estimate the size of a very small subpopulation from straightforward survey data.

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar
    steve curtis

    The political polling companies dont miss a beat. Back to selling their wares within days, but of course its a totally new product now…till next election.

    9 months ago