As Election Day draws closer, Americans are being inundated with polls about the state of the presidential race. A better question to ask may be what, exactly, are we trusting polls to do? If the answer is to predict the future, then trust in polls is misplaced. Four years ago, Trump won the White House despite trailing in most national surveys at the time.
Several factors explain this disconnect. Nationally, surveys in were quite accurate by historical standards. Polls in some key Midwestern battleground states overstated support for Hillary Clinton and understated support for Trump by not correcting for having too many college graduates in their samples. Some of these polling issues may have been unique to But others are constants that Americans would do well to keep in mind this year, particularly given the historic uncertainty caused by the coronavirus pandemic.
First and foremost, polls are snapshots in time. Elections indicate who wins, but not why. Politicians are often eager to claim that their victory represents a mandate, but the only thing an election actually reveals is that a majority of voters preferred one candidate over another — a decision that can be driven as much attraction as repulsion, and as much by partisanship and identity as by policy. But how can we know what voters think?
Politicians in earlier periods relied on newspaper editorial pages to assess community priorities, but few would suggest that this work nowadays given the dramatic decline in local newspapers and the increasing politicization of some news sources.
Protests can reveal public discontent, but it is hard to know how broadly the views of those passionate enough to take to the streets — or write letters or attend meetings — resonate in the society at large.
By proactively attempting to give everyone an equal chance of being heard, public opinion polls provide a way of obtaining the views of citizens who are uninterested or unable to express their political views otherwise.
To be clear, public opinion is important, but it cannot and should not wholly determine public policy or legislative action. Political leadership can, and should, help inform and shape public opinion — especially in a representative democracy where our elected officials often have more time, expertise, and awareness of the complex situations facing the nation than ordinary citizens.
After the election, it was clear that there were problems with pre-election polls. Heading into the election, pre-election pollsters had reasons for optimism. Not only did the pre-election polls correctly predict that the Democrats would recapture the House of Representatives, but pre-election polling practices had also changed and many polls now accounted for the importance of education. In addition, unlike the uncertain and unsettled electorate of , voters in were largely decided heading into Election Day.
Like , pre-election polls continued to drive campaign news coverage thoughout the cycle. At least 1, state-level presidential polls were conducted and publicly released — including in the last two weeks alone — and these polls resulted in many hours of coverage devoted to speculation about what the results meant, why the candidates were performing as they were, and what could change before Election Day.
One reason is many voters in the three critical battleground states of Wisconsin, Florida, and Pennsylvania made their voting decision at the last minute. A large majority of those late deciders voted for Trump, but polls taken before their decisions were made were not able to reflect that. State-level polls were off because they did not reflect the disparities between college and post-graduate educated voters and those voters with a high school education or less. Pollsters look at previous voting trends, Census reports, and other demographic data to help to determine their methodology.
College and post-graduate educated voters in previous years tended to vote in the same manner as those with a high school or less education. Both groups tended to vote Democratic in both and So, pollsters who surveyed these two groups of voters did not see a need to adjust their methodology or to weight respondents by education level.
They more or less lumped their results together and typical Democrat voters, and the results reflected an overestimation of support for Clinton. Pollsters could not have also known that there would be a significant increase in turnout in traditionally rural Republican areas compared to Those who felt led astray by surveys conducted during the U.
National pre-election polls in indicated that Hillary Clinton would win the national popular vote by a 3-point margin, and in fact she won by 2 points. The major problem was with state-level polls, many of which missed a late swing to Trump among undecided voters and did not correct for the fact that their responding samples contained proportionally too many college-educated voters who were more likely to favor Clinton.
A silver lining is that both of these problems can be overcome, to some extent, by more rigorous survey weighting and heightened attention to the possibility of late shifts in voter preferences. Why not? Because an election poll has an extra hurdle to jump: It not only has to measure public opinion, it also has to predict which of the people interviewed are going to vote and how they will vote — a notoriously difficult task.
There are a number of other ways we can measure the health of polling. One is to look at how polling on an issue tracks with real-world events. For example, on the issue of same-sex marriage in the United States, polls showed growing acceptance around the same time that advocates were winning statewide referenda legalizing it.
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