Posted by Simon Hix and Nick Vivyan.

We have updated our election prediction model, based on national voting intention results from all polls with fieldwork up to and including 26 April.  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.

As of 26 April, the national standing of the parties was 33.3 per cent for the Conservatives (up 1.0 per cent from our 19 April analysis), 26.5 per cent for Labour (down 0.3 per cent), and 29.3 per cent for the Lib Dems (down 0.8 per cent).  So, in relative terms the Tories may have gained very slightly since our 19 April analysis, but all of these changes are within the margin of error.

Here’s how these national vote shares might translate into seats under three different assumptions: (1) a uniform change in party support across constituencies; (2) differential changes in party support in each region of the country, based on the latest regional polling data from YouGov; and (3) differential changes in party support in key marginal seats, using the latest data from Ipsos-Mori polling data in 57 Labour-held constituencies where the Conservatives need a swing of 5-9 per cent to win.

Hix-Vivyan Seat Projections for 28 April

Hix-Vivyan pooling-the-polls model Comparison with other predictions
a uniform
national swing
regional swings
marginal seat swings
UK Polling Report Seat ProjectionElectoral Calculus Seat Projection
Last Checked28 April28 April28 April27 April27 April
Liberal Democrats981171039794
Other Parties3232333232
No. of seats Cons short of a majority6148604361
No. of seats Labour short of a majority71103788866

With a week to go until polling day, the Conservatives look set to be the largest party in the Commons but well short of a majority of seats.