Forecast update: 20 February 2015

Forecast main 150220

Last week, our forecast had the election as a tossup: the Tories and Labour each with a 50% chance of winning the most seats. This week, not much has changed. Our national polling average hasn’t moved, save for UKIP dropping a point to 14%, so it’s still Labour 33%, Tories 32%.

We now have Labour as very narrow favourites to emerge as the largest party, with a 51% chance to the Tories’ 49%. But, just as every week since our new model launched in January, it’s basically 50-50.

The chances of a Hung Parliament are up again, to 86%, as David Cameron’s chances of securing a majority are down to 8% and Ed Miliband’s stay on 5%

It is very likely that Labour, the Lib Dems, the SNP, the SDLP, Plaid Cymru and the Greens would have a majority of seats between them (our model gives an 82% chance of some combination of these having the required 323 seats). Whether Ed Miliband can convert that into a place in Number 10 remains to be seen, but our model suggests that’s more likely than David Cameron being able to remain.

Our central forecast is for the Tories to win 33.7% of the vote and 281 seats, and Labour to win fewer votes (31.4%) but one more seat (282). That combined vote share – 65.1% – for the two parties would be their lowest since 1918.


Date of forecast: 20 February 2015
Days till the election: 76

Inputted current average poll shares
Con: 32%
Lab: 33%
LD: 8%
UKIP: 14%
Others: 13%

Forecast GB Vote Shares (with 95% Prediction Intervals)
Con: 33.7% (29% – 38%)
Lab: 31.4% (27% – 36%)
LD: 10.2% (6% – 15%)
UKIP: 12.8% (8% – 17%)
Others: 11.9% (10% – 14%)

Forecast Scotland Vote Shares (with 95% Prediction Intervals)
SNP: 44% (40% – 48%)
Labour: 31% (27% – 35%)

Forecast GB Seats (with 95% Prediction Intervals)
Con: 281 (235 – 332)
Lab: 282 (233 – 324)
LD: 23 (13 – 37)
SNP: 40 (27 – 50)
PC: 3
Grn: 1
(May not sum to 632 due to rounding of sums of probabilities. Prediction intervals not yet available for UKIP, PC and Grn.)

Central forecast: Lab short of a majority by 41
(Criterion for majority now changed to 323 not 326, assuming Sinn Fein win 5 seats and do not take them.)

Probabilities of key outcomes
Con largest: 49%
Lab largest: 51%
Hung Parliament: 86%
… with Con largest: 41%
… with Lab largest: 45%

Probabilities of predicted government outcomes:
(See here for explanations and assumptions)

Con majority: 8%
Con+NDown: 0%
Con+ND+DUP: 6%
Con+ND+LD: 9%
… with Con+ND+DUP also possible: 6%
… without Con+ND+DUP also possible: 3%

Lab majority: 5%
Left (Lab+SDLP+PC+Grn): 4%
Left+LD: 26.5%
… with LD as kingmakers: 0.5%
… without LD as kingmakers: 26%
Left+SNP: 47%
… with Left+LD also possible: 26%
… without Left+LD possible: 21%
Left+SNP+LD: 25%
… with LD as kingmakers: 24%
… without LD as kingmakers: 1%

LD kingmakers: 24.5%
With a choice between Con+ND+DUP(+UKIP)+LD or
…Lab+SDLP+PC+Grn+LD: 0.5%
…Lab+SDLP+PC+Grn+SNP+LD: 24%

(Probabilities may not sum due to rounding)

4 thoughts on “Forecast update: 20 February 2015”

  1. I suggest you should remove North Down from your prediction analysis as potential Conservative support.

    North Down MP, Sylvia Hermon, Independent, is very very likely to win her seat back.
    Although she was previously a UUP MP, and is a unionist, she would at all support a Conservative Government, I fact, the UUP’s support for the Conservatives is the reason for her leaving the party and standing Independently.

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