Election polls are more accurate if they ask participants how others will vote - Phys.org
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Election polls are more accurate if they ask
participants how others will vote
18 November 2020, by Mirta Galesic and Wändi Bruine De Bruin
Most people know quite a bit about the life
experiences of their friends and family, including
how happy and healthy they are and roughly how
much money they make. So we designed poll
questions to see whether this knowledge of others
extended to politics—and we have found that it
does.
Pollsters, we determined, could learn more if they
took advantage of this type of knowledge. Asking
people how others around them are going to vote
and aggregating their responses across a large
national sample enables pollsters to tap into what is
often called "the wisdom of crowds."
What are the new 'wisdom-of-crowds'
Actual results as of Nov. 17 vote counts. Credit: The questions?
Conversation
Since the 2016 U.S. presidential election season,
we have been asking participants in a variety of
election polls: "What percentage of your social
Most public opinion polls correctly predicted the contacts will vote for each candidate?"
winning candidate in the 2020 U.S. presidential
election—but on average, they overestimated the In the 2016 U.S. election, this question predicted
margin by which Democrat Joe Biden would beat that Trump would win, and did so more accurately
Republican incumbent Donald Trump. than questions asking about poll respondents' own
voting intentions.
Our research into polling methods has found that
pollsters' predictions can be more accurate if they
look beyond traditional questions. Traditional polls
ask people whom they would vote for if the election
were today, or for the percent chance that they
might vote for particular candidates.
But our research into people's expectations and
social judgments led us and our collaborators,
Henrik Olsson at the Santa Fe Institute and Drazen
Prelec at MIT, to wonder whether different
questions could yield more accurate results.
Specifically, we wanted to know whether asking
people about the political preferences of others in
their social circles and in their states could help
paint a fuller picture of the American electorate.
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First, asking people about others effectively
During the polling, the order of Biden and Trump was increases the sample size of the poll. It gives
randomly varied across participants. Credit: The pollsters at least some information about the voting
Conversation intentions of people whose data might otherwise
have been entirely left out. For instance, many
were not contacted by the pollsters, or may have
declined to participate. Even though the poll
The question about participants' social contacts respondents don't have perfect information about
was similarly more accurate than the traditional everyone around them, it turns out they do know
question at predicting the results of the 2017 enough to give useful answers.
French presidential election, the 2017 Dutch
parliamentary election, the 2018 Swedish
parliamentary election and the 2018 U.S. election
for House of Representatives.
In some of these polls, we also asked, "What
percentage of people in your state will vote for each
candidate?" This question also taps into
participants' knowledge of those around them, but
in a wider circle. Variations of this question have
worked well in previous elections.
How well did the new polling questions do?
In the 2020 U.S. presidential election, our "wisdom-
of-crowds" questions were once again better at Credit: The Conversation
predicting the outcome of the national popular vote
than the traditional questions. In the USC Dornsife
Daybreak Poll we asked more than 4,000
participants how they expected their social contacts Second, we suspect people may find it easier to
to vote and which candidate they thought would win report about how they think others might vote than
in their state. They were also asked how they it is to admit how they themselves will vote. Some
themselves were planning to vote. people may feel embarrassed to admit who their
favorite candidate is. Others may fear harassment.
The current election results show a Biden lead of And some might lie because they want to obstruct
3.7 percentage points in the popular vote. An pollsters. Our own findings suggest that Trump
average of national polls predicted a lead of 8.4 voters might have been more likely than Biden
percentage points. In comparison, the question voters to hide their voting intentions, for all of those
about social contacts predicted a 3.4-point Biden reasons.
lead. The state-winner question predicted Biden
leading by 1.5 points. By contrast, the traditional Third, most people are influenced by others around
question that asked about voters' own intentions in them. People often get information about political
the same poll predicted a 9.3-point lead. issues from friends and family—and those
conversations may influence their voting choices.
Why do the new polling questions work? Poll questions that ask participants how they will
vote do not capture that social influence. But by
We think there are three reasons that asking poll asking participants how they think others around
participants about others in their social circles and them will vote, pollsters may get some idea of
their state ends up being more accurate than which participants might still change their minds.
asking about the participants themselves.
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Other methods we are investigating Provided by The Conversation
Building on these findings, we are looking at ways
to integrate information from these and other
questions into algorithms that might make even
better predictions of election outcomes.
One algorithm, called the "Bayesian Truth Serum,"
gives more weight to the answers of participants
who say their voting intentions, and those of their
social circles, are relatively more prevalent than
people in that state think. Another algorithm, called
a "full information forecast," combines participants'
answers across several poll questions to
incorporate information from each of them. Both
methods largely outperformed the traditional polling
question and the predictions from an average of
polls.
Our poll did not have enough participants in each
state to make good state-level forecasts that could
help predict votes in the Electoral College. As it
was, our questions about social circles and
expected state winners predicted that Trump might
narrowly win the Electoral College. That was
wrong, but so far it appears that these questions
had on average lower error than the traditional
questions in predicting the difference between
Biden and Trump votes across states.
Even though we still don't know the final vote
counts for the 2020 election, we know enough to
see that pollsters could improve their predictions by
asking participants how they think others will vote.
This article is republished from The Conversation
under a Creative Commons license. Read the
original article.
3/4APA citation: Election polls are more accurate if they ask participants how others will vote (2020,
November 18) retrieved 10 December 2020 from https://phys.org/news/2020-11-election-polls-accurate-
vote.html
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