#GE2015 FORECAST

In the week of their conference in Manchester, Labour have recovered the point they lost in the polling average last week, but it’s not quite enough for them to regain the lead in our forecast.
It’s extremely finely-balanced though – as close as it’s been since our forecast launched almost a year ago. Our model now gives the Conservatives a 51% chance of winning the most seats (down from 56% last week), to Labour’s 49% (up from 44%).
Once again, the four major potential outcomes – a Tory majority, a Labour majority, a Hung Parliament with the Tories as the largest party and a Hung Parliament with Labour largest – are all pretty much as likely as each other: they all have probabilities within the range of 23% to 26%.
Our central forecast is also incredibly close, with the Tories securing the most votes by just over 3 percentage points (with 35.6% to Labour’s 32.5%), but only winning 2 more seats (299 to 297).
In this particular Hung Parliament scenario, the Lib Dems’ 26 MPs would not be enough to give either a Tory-Lib Dem or Labour-Lib Dem coalition more than half of the Commons’ 650. However, either of these coalitions might be able to command the slimmest of working majorities once the Speaker, Deputy Speakers and Sinn Fein are discounted.

Date of forecast: 26 September 2014
Days till the election: 223
Inputted current average poll shares
Con: 33%
Lab: 36%
LD: 8%
Others (inc. UKIP): 23%
– UKIP: 13%
Forecast Election Day Shares (with 95% Prediction Intervals)
Con: 35.6% (±7.1, i.e. 29% – 43%)
Lab: 32.5% (±5.3, i.e. 27% – 38%)
LD: 11.4% (±7.6, i.e. 4% – 19%)
Implied point estimate shares for:
– Others (inc. UKIP): 20.5%
– UKIP: 11.6%
Forecast Election Day Seats (with approximate 95% Prediction Intervals)
Con: 299 (223 – 386)
Lab: 297 (214 – 368)
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 27
Approximate probabilities of key outcomes
Con largest: 51%
… with a majority: 25%
Lab largest: 49%
… with a majority: 23%
Hung Parliament: 51%
… with Con largest: 26%
… with Lab largest: 25%
(probabilities may not sum due to rounding)