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.

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