How good are referendum polls in the UK?

by Stephen Fisher and Alan Renwick

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? Continue reading How good are referendum polls in the UK?

EU referendum Combined Forecast Update

Stephen Fisher and Rosalind Shorrocks.

Our latest forecast based on combining other forecasts shows a big increase in the probability that Remain will win the referendum, from 70.5% last week to 76.1% today. Intriguingly this has only been accompanied by a small increase in the forecast share of the vote for Remain, from 53.8% in the last forecast to 54.3%.

Remain % share Leave % share Probability Remain wins
Betting markets 54.3 45.7 80.2
Prediction markets 79.1
Citizen forecasts 68.0
Expert forecasts 56.0 44.0
Volunteer forecasts 54.3 45.7 76.3
Polls 53.7 46.3 72.7
Poll based models 55.8 44.2 80.7
Non-poll based models 51.8 48.2
Combined forecast (mean) 54.3 45.7 76.1

(Individual forecasts collected in the evening of 24th May 2016.) Continue reading EU referendum Combined Forecast Update

The Historical Referendums and Polls based forecast, one month out

by Stephen Fisher and Alan Renwick.

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% on 10th May to 53% 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% of the vote in a month’s time. The 95% prediction interval surrounding this estimate has narrowed very slightly to ±12.5 points. So we are forecasting that Remain will win between 43% and 68% 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%, up from 72% two weeks ago.

Updated Combined EU Referendum Forecast

Stephen Fisher and Rosalind Shorrocks.

This is the latest of our weekly updates of our combined EU referendum forecast. There is once again very little change in the average forecast share of the vote, the average probability of a Remain win, or in any of the individual components of the forecast.

Share of the vote Remain Leave
Betting markets 54.4 45.6
Polls 52.1 47.9
Expert forecasts 56.0 44.0
Volunteer forecasts 54.2 45.8
Poll based models 54.6 45.4
Non-poll based models 51.8 48.2
Combined forecast (mean) 53.8 46.2
Probability that Remain wins
Citizen forecasts 68.2
Volunteer forecasts 73.7
Prediction markets 71.0
Betting markets 73.5
Polls 63.0
Poll based models 73.9
Combined forecast (mean) 70.5

Individual forecasts collected 17th May 2016. Continue reading Updated Combined EU Referendum Forecast

Updated Combined EU Referendum Forecast

Stephen Fisher and Rosalind Shorrocks.

This is the latest of our weekly updates of our combined EU referendum forecast. There is once again almost no change in the average forecast share of the vote or the average probability of a Remain win.

Share of the vote Remain Leave
Betting markets 54.3 45.7
Polls 51.3 48.7
Expert forecasts 56.0 44.0
Volunteer forecasts 54.3 45.7
Poll based models 55.0 45.0
Non-poll based models 52.0 48.0
Combined forecast (mean) 53.8 46.2
Probability that Remain wins
Citizen forecasts 68.5
Volunteer forecasts 74.0
Prediction markets 69.0
Betting markets 71.8
Polls 62.5
Poll based models 74.9
Combined forecast (mean) 69.8

Individual forecasts collected 10th May 2016. Continue reading Updated Combined EU Referendum Forecast

An Update on the Historical Referendums and Polls based Forecast

by Stephen Fisher and Alan Renwick.

We have published two previous forecasts of the result of the UK’s referendum on EU membership, which are based on current vote intention opinion polls for this referendum and on the historical experience of referendum polls and referendum outcomes in the UK and on the EU elsewhere. The main ideas behind this approach are set out here. This post offers an update. Continue reading An Update on the Historical Referendums and Polls based Forecast