Cellphones hamper US pollsters

Predicting vote made much harder

BOSTON: Many opinion polls show Democrat Hillary Clinton leading Republican Donald Trump in a tight race for the November 8 US presidential election, but any one of four factors may make the outcome harder to predict.

Among the challenges for pollsters: the historic unpopularity of both candidates, the potential Election Day voter response to the polls themselves, the growing abandonment of landlines for cellphones and the rise of online polling.

An average of polls compiled by RealClearPolitics.com shows Clinton beating Trump by 5.4 percentage points. Highlighting the difficulties, the range varies from plus-13 for Clinton to a straight tie.

Trump has said the election is rigged against him and this week he accused media organisations of tilting the polls deliberately, but he has yet to offer evidence to back up these claims.

Voter turnout in the past few presidential elections has been about 60 percent. But given both candidates’ low overall popularity, turnout this year may fall to as low as 52 percent, said Cliff Zukin, a professor emeritus of political science at New Jersey’s Rutgers University. That makes it hard to guess who might stay home.

A second pitfall is the effect of the polling itself on voters. Sociologists believe polls can weaken projected winners by making their supporters more confident of the outcome and, therefore, less likely to vote. Pollsters caution, however, that the effect of polls on the electorate can only go so far.

“If it were showing Clinton up by 2 points, then it’s certainly possible that it would be within the margin of error that Trump might win,” said Douglas Schwartz, director of the Quinnipiac University Poll.

One of the biggest factors in polling today is the prevalence of cellphones. About half of Americans have only a cellphone and no landline, according to Federal Communications Commission data. This makes it harder for pollsters to gather a truly random sample because US law prohibits computerised auto-dialling to cellphones and there is no central directory for cellphones.

This has led polling outfits to generally rely on lower sample sizes to come up with results.

Others conduct surveys online. This allows them to reach large numbers of people at lower cost. But because participants are volunteers in many cases, rather than selected at random, segments of the electorate may be left out.

The lower or skewed response in both cellphone and online polls can pose a challenge with pollsters having to adjust results to match the real world. To accomplish this, they weight more heavily the opinions of types of voters under-represented in their surveys. – Reuters

Hillary Clinton