Forecast update: 19 September 2014

Forecast b 140919

After losing their lead in our forecast last week, the Conservatives have rebounded this week for their strongest forecast in two months.

In the UK Polling Report Average, the Tories have recovered the point they lost last week, back to 33%. Meanwhile Labour have lost a point for the first time since the beginning of July, to 35%. (UKIP are down two, to 13%.) The two-point gap is the closest the Tories have been since early-2012, with the exception of a single week in mid-May when they were just a point behind Labour.

That puts the Tories back in front in our forecast, with their chances of winning the most seats rising from 48% to 56%, their highest since mid-July. Labour’s chances are down from 52% to 44%.

It’s still very finely-balanced, with a 51% chance that neither party gains a majority (down a touch from 52% last week). Our model gives the Tories a 29% of winning a majority (up from 22%), and Labour a 20% chance (down from 26%).

Our central forecast is for the Tories to win 303 seats (up from 295 last week), leaving them 23 seats short of a majority. Labour are 11 seats behind on 292, down from 299 last week. In that scenario, the Lib Dems get 26 seats with 11.5% of the vote, enough for a very slim majority coalition with the Conservatives, but not with Labour.


Date of forecast: 19 September 2014
Days till the election: 230

Inputted current average poll shares (from UK Polling Report)
Con: 33%
Lab: 35%
LD: 8%
Others (inc. UKIP): 24%
– UKIP: 13%

Forecast Election Day Shares (with 95% Prediction Intervals)
Con: 35.7% (±7.1, i.e. 29% – 43%)
Lab: 31.8% (±5.4, i.e. 26% – 37%)
LD: 11.5% (±7.7, i.e. 4% – 19%)
Implied point estimate shares for:
– Others (inc. UKIP): 21.0%
– UKIP: 11.4%

Forecast Election Day Seats (with approximate 95% Prediction Intervals)
Con: 303 (226 – 391)
Lab: 292 (208 – 364)
LD: 26 (21 – 33)
(Prediction intervals assume LD & others shares at central forecast, Con & Lab shares vary as per prediction intervals)

Central forecast: Con largest party, but short of a majority by 23

Approximate probabilities of key outcomes
Con largest: 56%
… with a majority: 29%
Lab largest: 44%
… with a majority: 20%
Hung Parliament: 51%
… with Con largest: 27%
… with Lab largest: 24%
(probabilities may not sum due to rounding)

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