Many Republican Polls Are Measuring a Unicorn Electorate

Recent elections around the world have not been kind to pollsters. In contests in Israel and Britain, and in a referendum in Scotland, pre-election polls all showed tight races that ended up being, well, not so tight. Although American pollsters have not had to explain errors of such magnitude, there were some danger signs in the last two elections in the United States, with some pollsters doing much better than others. On average, pre-election polls underestimated the magnitude of Obama’s victory in 2012 and of Republican victories in the 2014 midterms. There’s a variety of possible culprits for these discrepancies. One clearly is tied to the challenge in correctly measuring both the size and the composition of the electorate. There’s some evidence that the polls that underestimated Obama’s margin in 2012 erred by underestimating the non-white and Democratic share of the electorate. The problem in 2014, on the other hand, was a kind of mirror image. Many polls erred by counting drop-off voters—individuals who voted in presidential elections, but not in midterms—who happen to be more Democratic.

In an article earlier in the week, I discussed whether Iowa and New Hampshire polls were getting the electorate right. Given the prominence and importance of national primary polls in the Republican contest for deciding who is in and who is out of the first GOP presidential debate, and also creating the self-fulfilling impression of momentum, are these national polls getting the “who votes” question right? Are they correctly gauging the size and composition of their supposed target population, the Republican primary electorate?