Category Archives: EU referendum

A 50:50 forecast from the Historical Referendums and Polls based method

by Stephen Fisher and Alan Renwick.

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

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

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

The probability that Remain will win the referendum has fallen from 68% last week to just 51% this week. Continue reading A 50:50 forecast from the Historical Referendums and Polls based method

Combined EU Referendum forecast update

Stephen Fisher and Rosalind Shorrocks.

This week’s forecast shows another drop in the probability of a Remain win, this time to 67.7%. Part of the reason for the drop is the introduction of significant new data sources and methodological changes (detailed below). But it is also true that all of the component methods, including those without methodological changes, have seen drops in the probability of a Remain vote. By contrast the forecast share of the vote for Remain continues to hover around 54% as in previous forecasts.

Remain % share Leave % share Probability Remain wins
Betting markets 53.2 46.8 72
Prediction markets 70.6
Citizen forecasts 64.3
Expert forecasts 55.1 44.9  62.0
Volunteer forecasts 54.2 45.8 74.2
Polls 51.1 48.9 59.1
Poll based models 53.5 46.5 72
Non-poll based models 55.6 44.4
Combined forecast (mean) 53.8 46.2 67.7

(Individual forecasts collected on 8th June 2016.)

METHODOLOGY Continue reading Combined EU Referendum forecast update

Historical Referendums and Polls based Forecast Update

by Stephen Fisher and Alan Renwick.

Remain have continued their gentle slide in the polls. Last week our polling average saw Remain drop from 53% to 52%. Now they are on 51% 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% to 53%.

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

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

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.

Updated combined EU Referendum forecast

Stephen Fisher and Rosalind Shorrocks.

This week’s forecast shows the probability of a Remain win reduced to 71.9%, down from 76.1% last week. Once again the forecast share of the vote for Remain, at 53.7%, is similar to all our previous combined forecasts.

Remain % share Leave % share Probability Remain wins
Betting markets 54.1 45.9 73.7
Prediction markets 73.8
Citizen forecasts 68.4
Expert forecasts 56.0 44.0
Volunteer forecasts 54.3 45.7 76.1
Polls 51.4 48.6 63.6
Poll based models 54.5 45.5 76.0
Non-poll based models 51.8 48.2
Combined forecast (mean) 53.7 46.3 71.9

(Individual forecasts collected in the morning of 1st June 2016.) Continue reading Updated combined EU Referendum forecast

Forecast update for the Historical Referendums and Polls based Method

by Stephen Fisher and Alan Renwick.

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% to 52%. 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% to 54%. The 95% prediction interval surrounding this estimate has again narrowed very slightly to ±12 points. So we are now forecasting that Remain will win between 42% and 66% of the vote.

Overall the probability that the Remain vote will be larger than the Leave vote has dropped from 79% last week to 73% now. Continue reading Forecast update for the Historical Referendums and Polls based Method

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.

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

UPDATED COMBINED EU REFERENDUM FORECAST

Stephen Fisher and Rosalind Shorrocks

This is our latest update of our combined EU referendum forecast, updated weekly. There is no real change compared to last week in either the forecast share of the vote or average probability that Remain will win, with a clear consensus for a Remain win. This hides some movement in individual forecasts however, with the predicted probability of a Remain win from betting markets increasing, but decreasing from polls.

Share of the vote Remain Leave
Betting markets 54.6 45.4
Polls 51.3 48.7
Expert forecasts 56.2 43.8
Volunteer forecasts 54.8 45.2
Poll based models 55.4 44.6
Non-poll based models 52.0 48.0
Combined forecast (mean) 54 46
Probability that Remain wins
Citizen forecasts 67.9
Volunteer forecasts 74.0
Prediction markets 71.1
Betting markets 70.3
Polls 63.9
Poll based models 75.7
Combined forecast (mean) 69.3

Individual forecasts collected 3rd May 2016. Continue reading UPDATED COMBINED EU REFERENDUM FORECAST