To begin at the beginning: what was the story with Cleggmania Mark I? Was it just a dream? It is a truism of political science that what happens in election campaigns doesn't make any real difference. By the time the formal campaigning starts the voters pretty much know where they stand. They then have to wait patiently (or impatiently) for a few weeks while politicians and journalists get their knickers in a twist over imagined gaffes and surges, swings and comebacks. Once that is all over, people put their crosses just where they were going to put them anyway. But some recent research by Robert Goodin and James Mahmud Rice suggests that something more complicated might be going on. The polls, they reveal, don't fluctuate in the run-up to an election because respondents are simply humouring the pollsters with the pretence that their opinions are shifting - their opinions really are shifting. Looked at over a 40-year period, general elections in Britain and Australia show that there is usually a swing of up to five percentage points between the start and the end of a month-long campaign. Then on the day of the vote opinion swings all the way back again. Polls taken at the start of the campaign are invariably closer to the final result than the ones taken at the end. So it's not that people don't change their minds. They change their minds twice: once in response to the excitement of the campaign, and once in the privacy of the polling booth.

LRB 27 May 2010 | PDF Download