forecast | The Constitution Unit Blog

Stephen Fisher and Alan Renwick have developed a method for forecasting the outcome of the EU referendum based on current vote intention polling and analysis of opinion polling from previous referendums in the UK and around the world. In this post they introduce their model and present their initial forecast.

The UK will have a referendum on whether to remain in or leave the EU on 23 June 2016. We have developed a method for forecasting the outcome based on current vote intention polls and analysis of opinion polls from previous referendums from the UK and across the world.

In the run-up to the 2014 Scottish Independence referendum we wrote about how across various referendums there has been a tendency for the eventual vote for change to be lower than it was in polls over one-month out from referendum day, and for even final polls to overstate support for change. But these observations were based on relatively small samples of referendums.

Now, as part of a broader academic project, we are analysing over 1600 polls from 283 referendums in 41 democracies. For the purposes of forecasting the Brexit referendum outcome, we have used just referendums in the UK or on the EU. This still includes 848 polls from 45 referendums, and for the model specification we draw on the lessons from our analysis of the broader data set.

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This year’s general election result took almost everyone by surprise, including the pollsters, forecasters and other experts. On 3 June, Joe Twyman, Dr Ben Lauderdale, Dr Rosie Campbell, Professor Justin Fisher and Professor Matt Goodwin took part in a roundtable to discuss where the predictions went wrong and lessons for 2020. David Ireland offers an overview of the event.

The exit poll that came out at 10pm on 7 May took almost everyone by surprise. Over the course of Friday morning, the scale of the Conservative majority revealed itself, showing that even the exit poll had underestimated the Conservative support. What happened? How did the polls get it so wrong and what are the lessons for 2020? This blog highlights the key issues from a recent roundtable on GE2015 hosted by UCL’s Department of Political Science and the Constitution Unit and chaired by Dr Jennifer Hudson.

Joe Twyman, Head of Political and Social Research, YouGov

As one of many pollsters who had long predicted a hung parliament, Joe acknowledged YouGov didn’t get it right this time. He also, rather humorously, showed the range of Twitter abuse directed at him as a result.

Voting intention remained tightly balanced in the months leading up to the election, but YouGov’s polling revealed that the ‘fundamentals’ may not have been given enough weight in predicting vote share.Importantly, no party had ever come from behind on the economy and leadership to won an election before, and this election was not to be the first. The economy remained the single most important issue, and here, the Conservatives were significantly ahead. Similarly, Miliband never got close to Cameron on party leader ratings. Continue reading →