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.