FAQ: Question Wording
The wording of polling questions can have a huge impact on the answers – I will write a much longer article on that in the future. For the moment I want to look at the far simpler question of the wording used for voting intention questions. The differences here are very minor so this is consequently only a short article!
Firstly, here are the wordings used:
Ipsos MORI: How would you vote if there were a General Election tomorrow?
Populus: If there was a general election tomorrow, which party would you vote for? Would it be [rotate order] Conservative, Labour, Liberal Democrat, or another party – or would you not vote at all.
ICM: The Conservatives, Labour, the Liberal Democrats and other parties would fight a new election in your area. If there were a general election tomorrow which party do you think you would vote for?
ComRes: If there were a general election tomorrow, would you vote Conservative, Labour, Liberal Democrat or some other party?
YouGov: If there were a general election held tomorrow, which party would you vote for?
As you can see, there is no drastic difference between the pollsters, but there are some differences that may be making a subtle difference.
Firstly there is the issue of whether or not the question prompts by party name. While in the questions above only three of the pollsters include party names, in fact they all prompt by party name. Since Yougov survey’s are mostly selecting onscreen options, obviously the party names are there for people to tick. MORI would have done the same when they used to do their surveys face-to-face (interviewers use laptops to display the questions and record answers), I can only assume they now read out the party names afterwards.
Historically prompting by party name was a very significant difference between pollsters, as it gives a significant boost to the Liberal Democrats. A poll that includes the Lib Dems in the prompt tends to show their support about 2 points higher than one which doesn’t. These days that is no longer an issue as everyone does it, but it is still a consideration for minor parties like the Greens and UKIP. These are not normally prompted for, and prompting for them gives them significantly more support. The problem is, when they are compared to election results, polls that prompt for minor parties invariably overestimate their support. So while it seems unfair, the most accurate way of polling seems to be to prompt using the names of the three main parties (plus the SNP and Plaid Cymru in Scotland and Wales), but ignoring minor parties.
A more significant difference is in ICM’s wording which specifies “in your area”. This is very interesting since we know that people give very different answers if they are asked to say specifically how they would vote in their own constituency – people suddenly start taking into account tactical voting or what they think of their MP, and this normally increases Lib Dem support. ICM, as regular readers will know, invariably show the highest level of Lib Dem support and this difference in question wording could be a factor.