When a party goes up or down in the polls there is inevitably speculation as to why. Sadly it’s not normally very good speculation… there is always a temptation for people to follow the logic of I think issue X is very important therefore issue X is the cause of the recent shift in the polls. Inferences from polls are not always much better than that – people who are supporting party Y are more likely to think X, therefore X has caused the increased support for that party. It sounds okay, but what about issues A, B and C which weren’t asked in the poll?
Daily polling does at least give us an idea of when movements in public opinion have happened, and therefore make inferences about what events may have caused them. The graph below shows a five day rolling average of UKIP’s support in YouGov’s daily poll since the end of 2011.
You can see there are two big increases – the first was the Budget in 2012, nothing to do with immigration or Europe or any of those issues we associate with UKIP, the thing that co-incided with an increase in UKIP support more than anything else was the budget. My guess, given the demographic make up of UKIP’s vote, that the granny tax and the messages it sent out were the most important factor there. UKIP’s support then faded away a bit, had a couple of lumps and bumps during the autumn and then shot up again during November when there was an almost perfect storm for them – the run up to the EU budget summit, a decent performance in the police elections, the Rotherham fostering row, the speculation over a Con-UKIP pact and finally the solid by-election performance at the end of the month, all combining to produce far more news coverage than the party could normally dream of. It is possible that the gay marriage issue since then has helped keep their support up.
All of this is still a far cry from proving what causes the ups and downs in UKIP support, after all, correlation does not prove causality. There could have been other events at the same time that got less attention, but it is normally a fairly good pointer.
Note also the biggest drop in UKIP support, back at the end of 2011 at the time of David Cameron’s veto in Europe. As I wrote the other day, Europe isn’t actually the main driver of UKIP support, so if the Conservatives suddenly became more anti-European UKIP would not vanish like magic… but it is an issue that plays to the sort of values that drive UKIP voters, so neither is it irrelevant.