EU referendum forecast update: probability of a Remain win slides to 51 per cent

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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 across Europe. This week the forecast has taken a dramatic turn with the probability of a Remain win falling from 68 per cent last week to just 51 per cent.

Our forecast has taken a dramatic turn. Last week our polling average had Remain at 51 per cent after setting aside don’t knows. It has this week dropped a further two points to 49 per cent. This means Leave is ahead in our polling average for the first time, with 51 per cent.

The forecast share of the vote for Remain has correspondingly dropped from 53 per cent to slightly over 50 per cent.

The 95 per cent prediction interval is still ±12 points. So we are now forecasting that both Leave and Remain will win between 38 per cent and 62 per cent of the vote.

The probability that Remain will win the referendum has fallen from 68 per cent last week to just 51 per cent this week.

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EU referendum forecast update: probability of Remain win falls for second consecutive week

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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 across Europe. For the second consecutive week the probability of a Remain win has fallen and now stands at 68 per cent.

Remain have continued their gentle slide in the polls. Last week our polling average saw Remain drop from 53 per cent to 52 per cent. Now they are on 51 per cent after setting aside don’t knows.

The further one-point drop in our polling average has produced a one-point drop in the forecast share of the vote for Remain, from 54 per cent to 53 per cent.

The 95 per cent prediction interval is still ±12 points. We are now forecasting that Remain will win between 40 per cent and 65 per cent of the vote.

The probability that Remain will win the referendum is now down to 68 per cent.

The method behind this forecast is based on the historical experience of referendum polls and referendum outcomes in the UK and on the EU elsewhere, as discussed here.

Our polling average is constructed by taking the most recent poll from each company within the last two weeks. If a company uses both phone and online modes then both the most recent phone poll and most recent online poll are used. This applies just to ICM this week. The current average is based on the results of eight polls from seven companies, of which three were conducted by phone and five online. All polls are adjusted to account for the tendency for phone polls to be more favourable to Remain. This is done by adding 2.2 to the Remain share for online polls and subtracting the same amount for phone polls.

This post was originally published on Elections Etc. and is re-posted with permission.

About the authors

Dr Stephen Fisher is an Associate Professor in Political Sociology and the Fellow and Tutor in Politics at Trinity College, Oxford.

Dr Alan Renwick is the Deputy Director of the Constitution Unit.

EU referendum forecast update: probability of Remain winning falls to 73 per cent

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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 across Europe. Since last week’s update the probability of a Remain win has reduced from 79 per cent to 73 per cent.

The small shift towards Remain in the polls that we observed last week has been reversed. Setting aside don’t knows, our polling average for Remain has dropped back from 53 per cent to 52 per cent. Despite there being little difference between the headline figures for yesterday’s ICM phone and online polls, our estimate (and corresponding adjustment) for the typical difference between the two modes of interviewing has barely changed.

The one-point drop in our polling average has led to a corresponding one-point drop in the forecast share of the vote for Remain, from 55 per cent to 54 per cent. The 95 per cent prediction interval surrounding this estimate has again narrowed very slightly to ±12 points. So we are now forecasting that Remain will win between 42 per cent and 66 per cent of the vote.

Overall the probability that the Remain vote will be larger than the Leave vote has dropped from 79 per cent last week to 73 per cent now.

The method behind this forecast is based on the historical experience of referendum polls and referendum outcomes in the UK and on the EU elsewhere, as discussed here.

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Referendum polling in the UK has historically overstated support for change

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The differing outcomes produced by online and telephone polling during the EU referendum have led to a debate about the merits of each method. But perhaps neither is a good indicator of the final outcome. Stephen Fisher and Alan Renwick suggest that there is often a trend towards the status quo during referendum campaigns in the UK, and that even polls in the final week before a referendum have often shown more support for change than the result.

As online and telephone polls for the EU referendum continue to tell different stories about the contest, there is increasing debate about the relative merits of each method (e.g. here, here and here). Much of this debate is focused on which of the two modes is more accurate. Does Remain have a comfortable lead, as phone polls suggest, or is it too close to call, as the online polls indicate?

Perhaps neither is a good guide to the final outcome. In this post we reflect on the historical experience of polls for referendums in the UK. The graph shows the levels of support for the change option (excluding don’t knows) in polls and the final outcome for all ten referendums in the UK for which there was more than one poll in the final 30 days of the campaign.

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EU referendum forecast update: 79 per cent chance of Remain winning

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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 across Europe. Since the last update two weeks ago the probability of a Remain win has increased from 72 per cent to 79 per cent.

There has been a small shift towards Remain in the polls over the last two weeks. Excluding don’t knows, our polling average for Remain has moved from 52 per cent on 10th May to 53 per cent now. This figure is based on the most recent polls from each of seven companies: one from each but two from ICM (one by phone and one conducted online). The Remain share has been adjusted down by 2.15 points for telephone polls and up by the same amount for online polls to account for the relatively stable gap between these different methods in the levels of support they tend to give the two sides.

Using the historical experience of referendum polls and referendum outcomes in the UK and on the EU elsewhere, as discussed here, our latest forecast is for Remain to win 55 per cent of the vote in a month’s time. The 95 per cent prediction interval surrounding this estimate has narrowed very slightly to ±12.5 points. So we are forecasting that Remain will win between 43 per cent and 68 per cent of the vote.

Values closer to the middle of this range are more likely. Overall the probability that the Remain vote will be larger than the Leave vote is now 79 per cent, up from 72 per cent two weeks ago.

This post was originally published on Elections Etc. and is re-posted with permission.

About the authors

Dr Stephen Fisher is an Associate Professor in Political Sociology and the Fellow and Tutor in Politics at Trinity College, Oxford.

Dr Alan Renwick is the Deputy Director of the Constitution Unit.