Voters Believed Us and Expected a Clinton Victory: Can We Manage Expectations This Time?

Four years ago, Libertarian candidate Gary Johnson recieved 146,715 votes in Pennsylvania. Clinton lost the state to Trump by about 44,292 votes.

Some of the 49,941 votes for Jill Stein would have helped Clinton as well but one reason they eluded the Democratic nominee was that Clinton looked like a sure winner.

How do we know that voters believed the Clinton-favoring forecasts? If we look at the CBS/NYT poll from November 2016, we see that only about 16% of Johnson and Stein supporters thought Trump would win.

(My code is posted here.)

I don’t have data on how many third-party voters would have been willing to vote for Clinton four years ago, but we can see whether these voters are now leaning Democratic or Republican.

It turns out most third-party voters are not happy with what they got. The majority of Johnson and Stein voters are saying they support Biden — only 14 to 27% say they would vote for Trump in November:

Nationscape data (waves 1–50). Analysis: Jan Zilinsky.

Without revisiting the turnout arguments, it’s also hard not to notice that 2016 non-voters say they prefer Biden than Trump.

Restricting the cross-tabulation only to respondents who are registered to vote, Biden’s margin among people who didn’t vote in the last election increases to 18 percentage points:

Nationscape data (waves 1–50). Registered voters only.

If you wanted Biden to do well, you would hope that relatively disengaged people — those who sat out the last election, and those who said no to major-party nominees last time — will vote in November.

Avoiding faulty assumptions

The consensus that Clinton would surely win influenced the actions investigators, journalists, and also voters.

  • Messing et al. have documented that “probabilistic forecasts can give potential voters the impression that one candidate will win more decisively and may even lower the likelihood that they vote”. (Paper here.)
  • A new book tells us that “[a]mong [Comey’s] senior advisers, few gave much credence to the idea that Trump had a real shot of winning the election.”

So here’s an idea: this time, let’s not tell anyone that the outcome of the election is preordained.

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political science & economics (sometimes with 19th century methods)

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Jan Zilinsky

political science & economics (sometimes with 19th century methods)