Today’s YouGov poll shows a startling change in attitudes to the EU. The results suggest more people would now vote to stay in the EU than to leave it: 40% staying in against 34% wanting to leave.
That’s a big swing from two months ago, when 49% said they would vote to leave: 17pts ahead of those wanting to stay:
Shifts like these don’t just happen by themselves. But is it real, or is something going on with the polling?
Option 1: a change in opinion
There are grounds for thinking a real shift has happened. The last time ‘vote to stay in’ was this high was December 2011: just after Cameron’s walkout of the EU summit.
At that time, the suggestion that the UK would leave the EU moved from remote to seeming more possible. Perhaps people started responding to the polling question differently: saying “I’d vote to leave the EU” became less of an empty threat.
Maybe that’s what happened this time as well. Over the last couple of weeks, discussions about the UK’s future in the EU have dominated the news again. People have started thinking about their own view, and they’ve responded to YouGov with a more considered opinion, which has taken some people away from the ‘out’ camp.
So we have a plausible explanation – but it’s not the only possible answer.
Option 2: bad polling
Some polling is designed to find out what people would do if they’re exposed to certain information or arguments. If Tesco promised to make its beefburgers with only British ingredients, would you be more likely to shop there? If you’re told that 60% of people affected by the benefit cap are in work, would you be more likely to oppose it?
But other polling is supposed to be a pure measure of what people currently think. Questions like voting intent and the EU referendum should be in this category.
So for the EU referendum question to show accurately what people think, respondents shouldn’t be shown anything that might influence their response. In an ideal world, they’d only be asked about the EU, and then the poll would finish. But that would be expensive, so we have to accept that the EU question will go in a poll with other questions.
In that case, the other questions respondents see need to be consistent between polls. So if respondents are being influenced by the other questions, at least it’s happening in a comparable way.
But that’s not how YouGov have done it.