by Stephen Fisher and Alan Renwick.

The polls this week have been better for Remain than they were last week. Since this is our final forecast it makes sense for us to restrict our sample of polls to include in our polling average just the most recent poll from each company (or company-mode combination) over the last week. If we do this then our polling average finds Remain at 51 per cent after setting aside Don’t Knows. This is up two points from our polling average on Sunday. The two-point difference is partly due to restricting the sample from two weeks to just one, partly rounding error and partly to the fact that more of the polls than previously include Northern Ireland. So it is not clear whether the apparent movement towards Remain is real or not.

Our forecast share of the vote is 52 per cent for Remain, 48 per cent for Leave. This reflects an expectation of a 1.5-point rise in support for the status quo, based on the change that is visible on average between the final polls and the actual result in previous referendums in Britain or on the EU elsewhere. While this reflects the average historical experience we have explained here and here why the average may not be a very reliable guide.

The unreliability means there is a lot of uncertainty in our forecast. The 95 per cent prediction interval is considerably narrower than it was at the beginning of the week. But at ±10 points it is still very wide. So wide that Remain could reasonably be expected to get anywhere between 42 per cent and 62 per cent of the vote. Neither a comfortable Remain victory nor a comfortable Leave victory can be ruled out.

That said not all the possible outcomes in this range are equally likely. Our forecast probability that Remain will win the referendum is 64 per cent.

The methods behind our forecast

Continue reading Final forecast from the Historical Referendums and Polls based method →

by Stephen Fisher and Alan Renwick.

We offer our condolences to the family and friends of Jo Cox MP. We hope that it is not disrespectful of us to post this updated forecast now that the official campaigns have resumed.

Our polling average now has Remain at 49% after setting aside Don’t Knows.

From this we forecast Remain to get 50% of the vote.

The 95% prediction interval is only a little narrower than ±12 points. So Remain are forecast to win between 39% and 62% of the vote.

The probability that Remain will win the referendum is now 52%.

The methods behind our forecast

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 to BMG, ICM and ORB this week. The current average is based on the results of twelve polls from nine companies, of which six were conducted by phone and six online. All polls are adjusted to account for the tendency for phone polls to be more favourable to Remain. This is done by adding 1.75 to the Remain share for online polls and subtracting the same amount for phone polls.

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 →

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.