UK’s EU referendum highlights pitfalls of polling

February 26, 2016 10:39 am


UK, Feb 26 – Who will win? That’s the question everyone is asking before Britain’s June 23 referendum on whether to leave the European Union — but pollsters are struggling to provide convincing pointers.

“Polls should be taken but never inhaled” was the pithy verdict from John Curtice, Britain’s top expert in the field, when asked at a briefing in the Houses of Parliament this week whether voters should trust them.

There is currently an issue of credibility after polling companies failed to predict the result of last year’s general election, which Prime Minister David Cameron’s Conservatives won with a surprise outright majority.

Polls are appearing every few days in Britain’s newspapers. Some suggest a British exit from the EU is imminent, while others point to Britain staying in the EU by a comfortable margin.

On February 4, YouGov gave the “Leave” camp 45 percent support compared to 36 percent for “Remain”, prompting a flurry of headlines predicting Brexit.

Less than two weeks later, Ipsos MORI gave the lead to the “Remain” camp by 54 percent to 36 percent.

This week, after Cameron secured a deal to reset Britain’s relations with the EU in Brussels and popular London Mayor Boris Johnson joined the leave camp, YouGov put the two virtually neck and neck — 37 percent for “Remain”, 38 percent for “Leave” and 25 percent undecided.

“It’s quite confusing,” said Adam Drummond, research manager at pollsters Opinium, who have been doing online polling for private clients on the referendum.

‘Pressure’ to give an opinion

Who to believe? Experts offer some advice to those trying to understand what is really likely to happen.

First, be aware of the differences between polls conducted online and over the telephone.

Online polls tend to show the sides at roughly level pegging, whereas telephone polls lean towards a “Remain” lead of some 15 percent.

Matthew Goodwin, an expert in euroscepticism at Kent University, said there may be issues of “social desirability” among those responding to pollsters here.

He suggested that voters may be “a bit more reluctant to say they’re backing Brexit over the telephone to another person”, adding: “It’s a lot easier to just click it on a computer”.

Stephan Shakespeare and Anthony Wells of YouGov, which uses online polling, highlighted a similar point.

“In person-to-person dialogue, people feel pressured by the expectation of an opinion, and then it’s much more likely to be for the status quo rather than change,” they said.

Goodwin suggested it may be wiser to study a poll of polls, such as the one maintained by academics at the What UK Thinks website, rather than relying on one individual poll, which can only provide a snapshot.

The What UK Thinks poll of polls, which takes an average of the last six surveys, puts “Remain” on 55 percent support and “Leave” on 45 percent.

The high number of undecided voters, thought to be as high as 20 percent, is another complicating factor.

“At a general election, the vast majority of the electorate vote the same way each time,” said Katharine Peacock, Tom Mludzinski and Adam Ludlow of ComRes in a recent briefing paper.

“At a referendum, there is a much more ‘low information’ electorate, making any polling about the issue particularly sensitive to differences in the political engagement of the sample being surveyed.”

There is some encouragement for the “Remain” camp, though the innate conservatism of most voters.

“What generally happens in such referendums is that towards the end of the campaign period, a huge bulk of undecided people choose in favour of whatever the status quo option is,” said Drummond.

There is, of course another way to try and figure out which way the referendum will go follow the money.

Bookmakers Ladbrokes currently give odds of 1/3 for “Remain” compared to 9/4 for “Leave”, suggesting gamblers believe overall it is more likely Britain will stay in the EU.


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