Forecast #GE2017 – 4th June 2017


This is our latest forecast for the 8th of June 2017 General Election in the UK.

Why have you moved to a proper forecast? – From around a week out to the election, the levels of uncertainty around the final result begin to diminish. From today we can project forward to Thursday 8th and make much firmer predictions about where the final voting figures will be.

Will your forecast change between now and next Thursday? – Very likely. If a week is a long time in politics, it is an eternity in elections. We will see lots of opinion polls published between now and next Thursday and these will help us to tune our forecast and to identify any major changes in trends which we will reflect.

What does your forecast show? – We try to give as much information as possible, but only where it is statistically significant. We try to show a 50% confidence interval on the national vote share for the major parties and as the 8th of June comes closer we will endeavour to do the same for Scotland and Wales as well. We show a much narrower range of possible seats for each party than some other forecasts as we believe the wide range of seats, for example the wide range used in the YouGov model, makes the concept of a “prediction” almost meaningless. The range of seats we indicate is the narrowest one which we believe is possible to offer and is based on the mid-point of our forecast. It is the “most likely” outcome but we accept that it does not cover all possibilities.

What do you use for your forecast? – We use all the latest polling data, where available. We also look at the betting markets and other information to help guide our forecast. We calculate the interaction between the support for the parties on as local a level as statistically possible and then use this to run a Monte Carlo simulation of the election.

What do you predict will happen in Seat X? What is the probability of Party Y having more votes than Z? – As we approach the 8th of June we reduce uncertainity in our model and are able to answer questions like this. Whilst we do not automatically publish a prediction for each seat, we can indicate a most likely outcome if required and also probabilities of victory for each candidate.

I want to ask a question / get in touch – Write a comment below to get in touch.

Key Features

The overall summary of our forecast is “Modest Gains for the Conservatives”.

Our forecast begins to move towards the Conservatives after the weekend’s polling. In particular we see evidence of a strengthened position in Wales. We continue to examine the issues around turnout weighting and note with interest that the two companies with the most sophisticated turnout models, ComRes and ICM, have not only produced the largest Conservative leads but are also clustered together in their results.

Our forecast indicates that there is little sign of a Remain boost for the Liberal Democrats. We are predicting a slump for UKIP and our seat forecast shows them not picking up any seats.

Our Northern Ireland forecast is based on limited data.

UK Forecast

Party % Vote Forecast Change on 2015
 Conservatives 43.7% (41.5% – 45.9%) 348 – 355 +18 to +25
 Labour 35.4% (33.4% – 37.5%) 219 – 230 -12 to -1
 SNP 3.8% 41 – 48 -15 to -8
Liberal Democrats 7.7% (7.1% – 8.3%) 6 – 9 -3 to same
Plaid Cymru 0.5% 1 – 4 -2 to +1
Green 1.9% 1 same
UKIP 4.5% (3.4% – 5.6%) 0 -1
Speaker 1
Northern Irish 18

Most likely result – Conservative Majority of 54

We have specific Welsh and Scottish forecasts as well.

Scotland

Party % Vote Forecast Change on 2015
SNP 41.1% 41 – 48 -15 to -8
Conservatives 28.0% 8 – 13 +7 to +12
Labour 23.5% 0 – 4 -1 to +3
Liberal Democrats 6.4% 1 – 3 same to +2
Greens 0.4%
UKIP 0.7%

Wales

Party % Vote Forecast Changes on 2015
Conservatives 39.3% 16 – 20 +5 to +9
Labour 36.3% 16 – 21 -9 to -4
Plaid Cymru 9.7% 1 – 4 -2 to +1
Liberal Democrats 6.7% 0 – 2 -1 to +1
UKIP 6.7%
Greens 1.0%

Northern Ireland

Party % Vote Forecast Changes on 2015
DUP 28.5% 7 – 12 -1 to +4
Sinn Fein 27.0% 3 – 6 -1 to +2
SDLP 12.4% 1 – 3 -1 to +1
UUP 14.8% 0 – 2 -2 to same
Alliance 9.8% 0 – 1 same to +1
Independent 1 same
Greens 1.0%

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