Survation have published a poll of Derby North and South Derbyshire constituencies for the Mirror and Progressive Polling, which shows a boost for Labour in both seats. Full tabs are here. The polling methodology itself was largely along ICM lines (telephone survey, weighted by past vote, ICM style weightings on likelihood to vote, and refusals and don’t knows reallocated according to how they say they voted last time).
In Derby North, currently a Labour marginal, the poll found figures of CON 23%(-9), LAB 51%(+18), LDEM 11%(-16), BNP 10%(+6), Others 6%(+3).
In South Derbyshire, currently a relatively comfortable Conservative seat, the poll found figures of CON 32%(-14), LAB 51%(+15), LDEM 9%(-7), BNP 1%(-3), Others 12%(+9)
The precise shares of the vote aren’t that interesting, given they are based on 174 and 149 people respectively, and hence have very large margins of error, but the overall picture is of a big swing towards Labour. Labour’s performance isn’t radically different from national polls, but there is a sharp drop in Tory support, something national polls aren’t showing. It implies that the Conservatives are doing worse in Derby than elsewhere.
Now, a plausible explanation is that this is connected with the Bombardier decision… it is certainly possible for large industrial closures to have big effects on particular seats (an excellent example is Redcar at the last election, where one assumes the closure of the steelworks was a factor behind the massive swing).
However, it pays to remember that correlation does not equal causality. This could be a Bombardier effect, it could be that the Conservatives are doing worse in a lot of urban seats, or in Midlands seats, or something entirely different. We don’t know. The rest of the questions are of no use in determining salience of the issue – questions of the “How likely is X to affect your vote at the election” pattern are worse than useless (they give false prominence to an issue with no requirement to balance it against other issues, or any measure of how likely people actually are to change their vote).
Of course, in practice we are probably years away from an election (in the Redcar example I quoted above the steel plant was mothballed a matter of months before the election) and there are likely to be major boundary changes in the Derby area (I’d expect Mid-Derbyshire to get the chop, with consequential knock on effects) anyway, but an interesting local straw in the wind nonetheless.
UPDATE: Unconnected to this (well, no more connected to this than every other post I make), there’s a very good explanation of sample error from Ben Goldacre here.
