The problem stems from a number of causes but begins with a fundamental shift in the public’s relationship with the telephone. For decades, the vast majority of people had landlines that they answered faithfully and, when asked to take part in surveys, mostly did so. Today, home landlines are dying and, when asked over mobile phones to answer questions, a big majority declines.
"Telemarketing, from a pollster’s point of view, poisoned the well," said Charles Franklin, director of Marquette University’s survey operation. "Then came answering machines and caller ID. Most of the time, you never get a human to pick up now."
The paltry response rates come at a time of rising anti-establishment sentiment in U.S. primary elections reminiscent of the unpredictable races in other countries. Such sentiment has never been easy to measure, especially when predicting whether populist anger will turn into real votes.
With sample sizes often small, fluctuations in polling numbers can be caused by less than a handful of people. A new NBC News/Wall Street Journal national survey of the Republican race out this week, for instance, represents the preferences of only 230 likely GOP voters. Analysis of certain subgroups, like evangelicals, could be shaped by the response of a single voter.
Shifting demographics are also playing a role. In the U.S., non-whites, who have historically voted at a lower rate than whites, are likely to comprise a majority of the population by mid-century. As their share of the electorate grows, so might their tendency to vote. No one knows by how much, making turnout estimates hard.
To save money, more polling is done using robocalls, Internet-based surveys, and other non-standard methods. Such alternatives may prove useful but they come with real risks. Robocalls, for example, are forbidden by law from dialing mobile phones. Online polling may oversample young people or Democratic Party voters. While such methods don’t necessarily produce inaccurate results, Franklin and others note, their newness makes it harder to predict reliability.
The young, who increasingly communicate via text, are not only less willing to speak over the phone about political preferences; they are less interested in talking by phone about anything at all.