Mellman: The likely voter sham

Mellman: The likely voter sham
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New York Times data journalist extraordinaire, Nate Cohn, used Twitter last week to announce the Times was “switching to likely voters.” That is, their polls would now reflect the opinions of voters likely to turnout in November.

The Times is hardly alone, so it’s a propitious moment to trot out one of my favorite polling iconoclasms: focusing on likely voters can be a misleading sham.

At first blush, my assertion may sound foolish. After all, too many Americans don’t exercise their right to vote. Aren’t we just interested in those who do? Non-voters play no role in elections.

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True.

But my argument rests on two central premises. First, our methods for determining who is a likely voter aren’t very effective (particularly if you aren’t using a voter file). Second, we aren’t really interested in likely voters. We should rather be interested in the likely electorate and the two are not the same.

Pollsters usually assess a respondents’ likelihood of voting by asking them directly, sometimes buttressing that question with others that seem, in theory, to relate to turnout.

The simple, albeit unpalatable, truth is that these questions aren’t very potent in divining a respondents’ likelihood of voting.

Last year, political scientists Anthony Rentsch, Brian Schaffner and Justin Gross analyzed the 64,600 interviews from the 2016 Cooperative Congressional Election study and found just 64 percent of those who maintained they were “definitely” going to vote did so. Only 68 percent of those who claimed they had already voted actually cast a ballot at any point. Meanwhile, 18 percent of self-reported “less likely” did turn out, as did 9 percent of those who claimed they had no intention of voting.

That question may be particularly blunt, but more complex items haven’t proved superior.

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Among those who scored the highest on Gallup’s multi-item scale in 2014, 83 percent voted, but 17 percent didn’t. Moreover, more than 20 percent of those who did cast ballots scored at the bottom end of the scale and would have been removed from the “likely voter” pool.

What about surrogates like “enthusiasm?”

In one race, we found among those “very” enthusiastic, 88 percent voted; among those who were “somewhat” enthusiastic, 83 percent turned out; and among those “not too” enthusiastic, a slightly larger 85 percent turned out. No relationship.

Gallup found the electorate’s aggregate enthusiasm unrelated to actual turnout as well.

So, the truth is, we just don’t have very good questions to separate “likely” from “unlikely” voters.

But even if we did, we’d be making a mistake to just survey likely voters.

“Likely” and “unlikely” are probability statements. Assume for a minute a likely voter has an 80 percent chance of voting. An unlikely voter has a 20 percent chance of showing up to the polls.

That means out of every 100 likely voters, 20 will not show up, while 20 of every 100 unlikely voters will.

There’s never been an electorate comprised exclusively of likely voters. In the foregoing example, the greatest likelihood is that 20 percent of those who turnout will be “unlikely voters.”

Our goal shouldn’t be finding which individuals are and are not going to vote, but rather constructing a sample that reflects the likely electorate, which includes some more, and some less likely, voters.

Open the vault to consider an example from a decade ago, when Senate Democratic Leader Harry ReidHarry Mason ReidDemocrats fear Russia interference could spoil bid to retake Senate Graham signals support for confirming a Supreme Court nominee this year Trump signals he will move to replace Ginsburg 'without delay' MORE (Nev.) faced a tough race.

Time/CNN released a poll that like every other (except ours) showed Reid behind, in this case by 2 points. However, though the pollsters ignored “unlikely voters” in their analysis, they were surveyed, and Reid led by 30 with this segment.

By excluding them completely, the poll proved wrong. Had those unlikely voters comprised 20 percent of the sample the pollsters used — had they focused on the likely electorate instead of on likely voters — they would have done better, showing Reid ahead, within a point of his eventual margin.

Beware the siren song of likely voter polls.

Mellman is president of The Mellman Group and has helped elect 30 U.S. senators, 12 governors and dozens of House members. Mellman served as pollster to Senate Democratic leaders for over 20 years, as president of the American Association of Political Consultants, and is president of Democratic Majority for Israel.