ICM has just released a constituency poll of Sheffield Hallam. Before a spiral-of-silence adjustment, Nick Clegg is on 40%, and his Labour challenger Oliver Coppard is on 36%. These figures are based on responses from 336 individuals, and so have a margin of error of 5.3%.
This compares with a recent Lord Ashcroft poll, which showed Clegg on 36%, and Coppard on 38%, but without naming the candidates. These figures were based on responses from 733 individuals.
Given these numbers and their associated margin of error, it’s not clear to me that we can conclude much about the relative merits of naming candidates versus not naming candidates. Suppose Clegg wins by 38% to Coppard’s 37% — we would be none the wiser.
Of course, there are other reasons for thinking that constituency polls which name candidates should be more accurate than constituency polls which do not name candidates.
The argument for naming is simple: voters in ballot booths are given a list of names; polls estimate what happens in the ballot booth; therefore polls should use the same prompts found in the ballot booth.
The argument against naming is more complicated, and may trade (entirely on in part) on the survey mode.
Suppose you receive a phone call from a pollster. Being a frequent consumer of polls, you oblige. You are given a list of names, but the list is quite long. You can’t quite remember the name of the Labour candidate, but you’ve heard of that Nick Clegg. Unwilling to look foolish in the eyes of the interviewer, you say, “Clegg, he’s the one”.
In other words, naming candidates in phone surveys biases responses to the most well-known candidate.
This name recognition effect probably doesn’t make sense to people with strong party identification. But there are fewer and fewer such people around, and there’s a long history of public opinion research which suggests that public opinion doesn’t really exist outside of a particular measurement context.
Ideally, all parties which conducted named-candidate polls (I’m looking at you LibDems!) will release these polls after the election so that they can be compared to the nearest (in time) Ashcroft poll. Only then will we be able to get some idea of the relative accuracy of named versus unnamed candidate polls across a range of constituencies.
Comments welcome below!