In the latest YouGov/Xbox poll, the pivotal state of Ohio showed slightly more Romney supporters than Obama supporters. But, when asked who they expect to win Ohio, the same respondents predicted Obama would win their state. Justin Wolfers and I have conducted an exhaustive research project on the power of expectation polling, and the evidence is overwhelming: when the intention (i.e., support) and expectation of respondents in a poll point in opposite directions, the expectation is correct over 75 percent of the time.
The YouGov/Xbox poll on Monday, October 29 asked respondents which candidate they were likely to support (their intention) and which candidate they thought would win their state (their expectation). We interviewed 12,479 respondents throughout the United States, 642 of who live in Ohio. Of the Ohioan respondents who supported either Obama or Romney, 48.3 percent supported Obama (versus 51.7 for Romney). Yet a notably larger 51.1 percent of these same Ohioan respondents, who reported an expectation that either Obama or Romney will win, predicted Obama to win their state of Ohio (versus 48.9 percent for Romney).
One explanation for why the expectation question is more meaningful for forecasts is that it incorporates more information. Every person possesses a batch of both public and private information about the election, and when a pollster asks them about their intention, the pollster is extracting only a small portion of that information; the pollster is just getting the respondent's support on that day. The expectation question captures information about the respondents social network (e.g., who the respondent thinks her friends and family will vote for) and more public information (e.g., what the respondent is seeing in the news), along with the respondents' intention to vote and support for one or the other candidate. Our paper shows that the expectation question has the forecasting power, relative to the intention question, of asking 10 times as many random respondents.
The standard intention question has dominated the polls for 75 years because it implicitly looks like the expected vote share, which is an outcome people can easily wrap their heads around. If we find that Romney is up 51.7 to 48.3 percent in our poll of the intentions of Ohio voters, one could implicitly assume that the likely vote share will be 51.7 percent for Romney to 48.3 percent for Obama. But most of us do not care about the vote share in Ohio; we care about who is going to win Ohio. If we state that Obama is up 51.1 to 48.9 percent in our poll of the expectation of Ohio voters, this number does not correspond directly to any one single outcome, but is much more likely to point towards the eventual winner than the poll of voter intention!
Of course, Ohio is just one piece in a bigger puzzle, the Electoral College; while our nationwide respondents are nearly even on whom they will vote for, they decisively expect Obama to win the election. Our October 29 poll had 50.4 percent support for Obama to 49.6 percent support for Romney (in major party support), a razor thin margin. However, 54.3 percent of the same people, on the same day, in the same poll, expect Obama's reelection, while just 45.7 percent expect Romney to win.
In the next few election cycles, randomly selected respondents from representative samples will get more and more expensive to contact, and we are very cognizant of that when we consider the goals of YouGov/Xbox poll. We want to provide meaningful insight into the current election, while also testing cutting edge graphical interfaces and questions that might promote even more accurate forecasts of election outcomes down the road. We encourage you to keep refreshing Huffington Post's Pollster's list of the Ohio intention polls all day (I know I do), but also look forward to a cycle or two from now when new questions and techniques break into the mainstream. We hope that our research being conducted in this poll will help to lead the way.
Mike Malecki, Doug Rivers, and Brian Stults (YouGov) contributed to the data work of this article. In the interest of disclosure, I help run the YouGov/Xbox poll in my capacity as an economist at Microsoft Research.
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