Do people switch during polling interviews?

I am grateful to Anthony Wells of UK Polling Report for picking up this oddity in the Ipsos-Mori poll. As can be seen two questions were asked – “How would you vote if there were a General Election tomorrow?” and a second “And how would you vote if there were a General Election held later this Autumn?”

For the former the widely reported headline figures had a 7% Labour lead. For the latter the margin drops to 5%.

On the face of it you would have thought that the same respondents would have produced the same answer to each question. Surely you don’t think – “well I’m Labour at the moment but in a few weeks I’ll be Tory”?

It would have been good to get a response from Bob Worcester when he was doing the Q&A session on the site here this morning.

This has got me thinking about those polling questions we had while Blair (remember him?) was still PM. People were asked how they would vote if there was an election tomorrow and then they were asked what they would do if Brown and Cameron were the leaders. In virtually every survey the Tories did better on the second question.

The view taken by me, amongst others, was that there was something about Brown that was turning off voters. Judging by these Mori responses it maybe that some people move to the Tories in the course of interviews.

Anthony notes, however, that “A week or two ago we were told that Labour’s private polling showed them 7 or 8 points ahead, but asked how people would vote in an autumn election it shot up to a 14 point lead”. This seems to be the opposite effect – except we don’t know with private polls what the questions were and the order that they were put.

Odd.

Mike Smithson