The most obvious solution to the problems with telephone polling is to administer polls online. That is a solution to the burgeoning cost of polling but not to the problem of whether the sample is representative of the electorate. Internet polling is less expensive and many companies provide polling panels that can mirror population demographics. But there is no way around the reality that people who are less interested in politics are disinclined to complete polls about politics even if they are interested enough to vote.
Internet respondents for the most part (there are exceptions) are people who have signed up to be on a panel and take a lot of polls. Should we assume that those who subscribe to a panel in exchange for a reward of some kind are representative of those who do not? I do not think so – especially when the invitation to complete the poll often tells you what it is about. (As a panelist, I chose to complete recent polls on feminism and on the Supreme Court but not on several other topics).
One group that is often underrepresented in both telephone and online polls are people in the middle of the political spectrum. In 2018, most voters were knew early on which party they would support, particularly in federal races (at least according to the polls). The election depended on voter turnout patterns and the relatively small number of people in the middle who were undecided, conflicted, not yet paying attention, more disinterested, or considering split tickets.
Voters in the middle are less likely than rabid partisans to want to share their political views whether probed online or on the phone. If you are tired of arguments about President Trump from either perspective, you are less likely to agree to spend 10 or 15 minutes talking (or writing) about him. Internet poll results often have even fewer undecided voters than telephone polls.
Luckily for the pollsters, the middle was a small group in this year’s election and so the absence of people in the middle did not skew too many polls. Some polls were wrong in Ohio because voters in the middle were disproportionately likely to support Republican Mike DeWine for Governor and Democrat Sherrod Brown for U.S. Senate. Those who were careful to poll the middle correctly predicted the result in each race. Those who polled more partisans and fewer voters in the middle got it wrong.
Online polling is also prone to leave out another significant group: people who are not online. Telephone polling tells us that 80-85 percent of voters are online but there is still 15 to 20 percent who say they are not. Combining online and telephone samples can fill that gap – except they will both leave out those people who simply – for whatever reason – do not want to be polled.
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