Articles and Analysis


Moore: Gallup's "Swing Voters" - A Major Underestimate?

Topics: David Moore , Gallup , NBC/Wall Street Journal , Newsweek , Time , UNH Survey Center , USA Today

Today's Guest Pollster article comes from David W. Moore, a senior fellow with the Carsey Institute at the University of New Hampshire. He is a former vice president and senior editor with the Gallup Poll, where he worked for 13 years, and is the founder and former director of the UNH Survey Center. He manages the blogsite, Skeptical Pollster.com.

In a recent post, Gallup's Jeff Jones reports that for the first time this election cycle, Gallup has measured the number of "swing voters" in the electorate. That's certainly a step in the right direction, but one might well wonder why it took so long for pollsters to admit that there is a substantial proportion of the public not committed to a candidate.

According to the post, Gallup finds that only 6 percent of "likely voters" are undecided as to which presidential candidate they will support. That number defies credulity. With five months to go in the campaign, neither major candidate the incumbent, no vice presidential candidates chosen, and no debates between the presumptive nominees, Gallup wants want us to believe that 94 percent of voters have already made up their minds? Yes, indeed! Not only that, CNN says 99 percent are decided. Time says 92 percent. Newsweek claims 87 percent. USA Today with Gallup says 97 percent. ABC/Washington Post - 96 percent. The NBC/Wall Street Journal poll says 90 percent. (For sources, see The Polling Report.)

With all these major media polls (not to mention numerous other polls not affiliated with the major news media organizations) in rough agreement that about nine in ten voters or more have made up their minds, any challenge to this conventional wisdom may seem futile. But here's something to consider. In a Sept. 3-5, 1996 Gallup poll, 40 percent of voters said they were undecided about whom they would support in the November presidential election between Robert Dole and Bill Clinton. How could such a large number be undecided in that poll - taken after the major party conventions and with just two months to go before the election, in which there was a popular incumbent candidate - and yet so few voters admit they are undecided in the current polls?

The answer, of course, lies in the way the voting question is asked. The standard vote choice question, which dates to 1935 when George Gallup first asked about presidential preferences, is deliberately designed to obfuscate the number of undecided voters. Gallup knew that the press wouldn't be interested in results that showed perhaps a majority of voters undecided months before an election, so he asked respondents which candidates they would vote for "today."1 And for the past seven plus decades pollsters have blindly followed that same format. In the September 1996 poll, however, Gallup abandoned the standard vote choice question, and instead first asked voters if they had even made their decision as to which candidate they would support. In that context, 39 percent said they hadn't, and an additional one percent were unsure.

In the current Gallup report, mentioned at the beginning of the article, Gallup retains the forced-choice standard format, but follows up by asking respondents if they could change their minds before election day. Those who said they could - 9 percent who initially said they would vote for McCain if the election were held "today," and 8 percent who initially favored Obama - were added to the six percent who initially said they were undecided, producing a 23 percent group Gallup characterizes as "swing voters."

Thus, according to Gallup, about a quarter of the electorate is up for grabs. I'm skeptical about that number - I suspect the percentage is much higher, perhaps even greater than the 40 percent measured by Gallup late in the 1996 campaign. But at least it's a recognition that there is a substantial number of voters who are not yet committed to a candidate.

Still, I would argue that most of the swing voters are not people who "could" change their minds before election day, as Gallup asserts, but rather people who have not yet even decided whom to support. Gallup (and any other national poll), of course, could test that proposition. All they need to do is replicate the question that Gallup asked in its September 3-5, 1996 poll: Ask voters up front if they have made up their minds whom they will support in November.2 My prediction - much more than a quarter of the electorate is up for grabs in 2008.

1 Three times in 1935, Gallup asked if respondents would vote for Roosevelt "today." The first time he pitted Roosevelt against anyone was in January 1936, when he asked: "For which candidate would you vote today - Franklin Roosevelt or the Republican candidate?" See George H. Gallup, The Gallup Poll: Public Opinion 1935-1971, Volume One (New York: Random House, 1972), pp. 1-10.

2 The exact wording is, "Have you made up your mind yet about who you will vote for in the presidential election this fall, or are you still deciding?"



I think your missing a key point about the methodology of the question- If the election were held today you wouldn't be able to be decided, you would have to choose somebody or stay home- therefore the level of "undecideds" measured this horserace question used by almost all major pollsters should should speak to the quality of the interviewers (whether they successfuly got the respondent to lean one way or the other).

So when you say:

"Newsweek claims 87 percent. USA Today with Gallup says 97 percent. ABC/Washington Post - 96 percent."

you are not being fully accurate because the question is measuring a response to a hypothetical situation in which "undecided" is not a valid response- if the question were administered perfectly there would be no so-called undecideds.

I also think your off-hand estimation of undecided voters is overblown- how would you define making a decision- self-rports of indecision could just as equally be a form of social desirability bias against acting like a hardcore supporter.



Agree or disagree, it's hard to buy an argument from someone who thinks there's still "five months to go in the campaign".



I think the writer may also be underestimating the level of disgust with the Bush administration and how many folks have decided anything is better than yet another Republican administration. There may be some undecided in the republican ranks but in terms of anyone leaning left at all they have made their choise...and it isn't John McSAME!


Mark Blumenthal:

David Moore is having trouble posting comments. He asked me to post the following:

The fallback excuse of media pollsters when they are challenged about the interpretation of their results is that they are asking only a hypothetical question "if the election were held today," thus exonerating them from the
misleading interpretation that everyone makes. The resulting numbers are treated by everyone, including pollsters who ask the question, as an
accurate reflection of what people are thinking today about the election. But that interpretation is clearly false -- it's impossible to believe that over 90 percent of voters have made up their minds "today" about their vote for president.

Whether I am overestimating the undecided vote is an empirical question. Let Gallup (or other pollsters) directly ask voters if they have made up their minds. While no question is perfect, the refusal of media pollsters to try to estimate the undecided vote -- and instead (almost) always ask the hypothetical question about the election being held "today" -- means
that the percentage of the electorate that is up for grabs is continually suppressed.

What poll even tries to measure the percentage of voters who are still trying to figure out whom to vote for? Don?t you think that is an important part of understanding the electorate in July of 2008?

The Gallup poll was taken in mid-June (15-19), close to five months before the election.


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