The ‘nowcast’ for May 2015 which gives the Lib Dems 28 MPs

by Stephen Tall on November 25, 2014

Over at the polling website May2015 (part of the New Statesman stable) Matt Singh has asked the straightforward question, ‘How are the Lib Dems polling and will they survive in May 2015?’ Except it isn’t all that straightforward…

First, there’s the issue that the different polling companies don’t agree on what the current Lib Dem rating actually is. In the last fortnight, the party’s been rated as low as 5% (Opinium) and as high as 11% (ICM): that’s a difference outside the margin of error you might expect.

The divergence is primarily down to what’s known as ‘house effects’ – ie, different polling companies adjust their figures to be nationally representative in subtly distinctive ways.

For instance, ICM assumes around half the voters currently saying ‘Don’t know’ will return to the party they voted for at the last election; however, YouGov excludes them altogether. As previous Lib Dem voters are more likely to be classified as ‘Don’t knows’ at the moment, this is the biggest single reason why ICM’s rating is most generous to the Lib Dems and YouGov’s less so.

My long-held theory is that Lib Dem-inclined voters are most likely to make up their minds latest (or to be voters who are normally supporters of other parties who decide to vote tactically for the Lib Dems in the final days of the campaign) and that this is what accounts for the traditional uptick in Lib Dem poll ratings during general election campaigns. It is also why, by the end of the campaign, pollsters generally converge on what the Lib Dem rating will be, even though their methodologies which currently produce different results stay the same.

Poll ratings converted into actual seats

The most interesting part of Matt Singh’s analysis is an in-depth look at what the current Lib Dem poll ratings imply about how many seats the Lib Dems will win in May 2015.

On a uniform national swing, based on the Lib Dems’ current 8% average rating the party would win 23 seats. Long-standing readers will understand why this threshold is of particular interest to me (my 2013 pledge to run naked down Whitehall kicks in if the Lib Dems don’t hit the 24 seat mark).

However, it’s widely accepted that Lib Dem MPs — embedded “like cockroaches” ((C) Tim Farron) in their own constituencies — often buck national trends. The constituency polling by Lord Ashcroft this years bears out that this incumbency boost persists in the face of the Lib Dems’ national difficulties. The incumbency boost obviously doesn’t exist where an MP is standing down; however, MPs elected in 2010 will likely get a first-time re-election bounce.

Taking all this into account, along with the current SNP surge which threatens the party in Scotland, Matt Singh calculates a ‘nowcast’ of Lib Dem fortunes next May:

Thus we arrive at a “nowcast” of 28 holds, 12 losses to Labour, 10 losses to the Conservatives and 7 losses to the SNP, including 4 seats where the SNP plus another party relegate the Lib Dems to third place.

This is just a summary; you can read his full post here. And of course a ‘nowcast’ is just that: a snapshot of the Lib Dems’ chances next May based on current polling. A lot could still change.

After all, in November 2009 the Lib Dems were averaging 17.5%, yet won 23% the following May. To be clear, I’m not expecting that kind of boost this time round: the circumstances are massively different. My current expectations are more in the 10-14% range. Which end of the spectrum it is will depend on the next 162 days.

* Stephen Tall is Co-Editor of Liberal Democrat Voice, and editor of the 2013 publication, The Coalition and Beyond: Liberal Reforms for the Decade Ahead. He is also a Research Associate for the liberal think-tank CentreForum and writes at his own site, The Collected Stephen Tall.