The polling differential in the marginals that would mean that we should be adding 5 to the LAB leadJanuary 15th, 2014
Are the blues really doing so much worse in the battlegrounds?
Back in September Lord Ashcrooft published his 12,083 sample phone polls showing that LAB was doing substantiality better in the key battlegrounds than in the country as a whole.
The idea that something different was happening in the marginals was given greater credence last month when Survation, in its series of constituency polls for UKIP donor, Alan Bown, also had Labour doing better.
The broad scale of the swing was 8.5% from the Tories since 2010. A national comparison poll carried out by Lord Ashcroft had just a 6% swing.
Before the Chritstmas break in a robust defence of his firm’s methodology on PB Survation’s Patrick Brione wrote:-
“…despite the prompting differences and other criticisms that have been levelled at our methodology, the key result from both Lord Ashcroft’s and Survation’s constituency polls is exactly the same. The Conservatives are significantly underperforming their national average across key marginal seats, regardless of where UKIP is pinned at..”
It should be emphasised that polls of marginals are carried out specifically for this purpose – to establish whether there is a different pattern in the constituencies that will decide the election than the overall national picture.
I find the gap between the national and marginals almost inexplicable for as it stands at the moment we should be adding about 5 points to the LAB lead in national polling to get a picture of what is happening in terms of seats changing hands.
What is going on? As I’ve pointed out before the Ashcroft polling found more than double the proportion of 2010 LDs had switched to LAB compared with his national comparison poll.
What the marginals polling does do is to try to get respondents to think specifically about their local situation. This would cover dynamics such as incumbency and tactical voting. Ashcroft has a two part voting question to highlight this.
Whatever I’ve yet to come to a conclusion on this. Do I believe the marginals polling or the national? We really need more of the former.