We have updated our election prediction model, based on national voting intention results from all polls with fieldwork up to and including 19 April – hence, taking into account the full set of polls after the first TV leaders’ debate. Here is a figure showing the time trends in our “pooling the polls” analysis. The dots in the figure show the results from the various polls and the shaded areas around the lines are the 95 per cent confidence intervals around the mean standings of the parties.
Time trends in Hix-Vivyan ‘Pooling the Polls’ analysis: January – April 2010
As of 19 April, the national standing of the parties was 32.3 per cent for the Conservatives (down 4.2 per cent from our 20 March analysis), 26.8 per cent for Labour (down 3.7 per cent), and 30.1 per cent for the Lib Dems (up 9.9 per cent). Looking across the polls, the performance of Nick Clegg in the TV debate appears to have shifted Lib Dem support upwards by about 9-11 per cent, at the expense of both Conservatives and Labour.
What would these numbers mean in terms of seats in the Commons?
The following table shows how these national vote shares might translate into seats under different assumptions: namely, (1) a uniform change in party support across constituencies, and (2) differential changes in party support in each region of the country, based on the latest regional polling data from YouGov.
Hix-Vivyan Seat Projections for 21 April
|Hix-Vivyan pooling-the-polls model||Comparison with other predictions|
|UK Polling Report Seat Projection||Electoral Calculus Seat Projection|
|Last Checked||19 April||19 April||20 April||20 April|
|No. of seats Cons short of a majority||80||67||30||71|
|No. of seats Labour short of a majority||64||67||89||59|
In other words, if we assume that changes in votes between the parties since 2005 translate more or less uniformly across constituencies, then Labour has a good chance of being the largest party in the Commons, despite trailing the Conservatives by more than 5 per cent in the polls.
However, if the current regional standings of the parties is a better predictor of constituency-level performance in the election, then Labour and the Conservatives could be neck-and-neck in the Commons.
Either way, given the best currently available information about the way parties’ votes are distributed across constituencies, the Lib Dems are likely to be at least 100 seats short of Labour and the Conservatives even if it is a three-way battle in the national polls.