Populus Perspective

In this issue

• The big picture
• Debate in context
• Time for a change – to whom?
• Whose policy?
• Brand effects

The big picture

There have been more than thirty opinion polls published since Gordon Brown called the general election – an average of more than three a day. At times they have seemed to show radically different pictures of party support. But the golden rule of reading opinion polls is to remember what relatively blunt instruments they are: most of the differences between the ratings for the three main parties from one poll to another are within the margin of error and are probably statistically meaningless.

Polls ought to scatter either side of a mean, within their defined margin, so the best way to read them is, as in the chart below (which shows all polls published this month), in batches, as a series of dots. The true level of party support should lie on the trendline through the scattered poll numbers. As the chart shows, not much has changed. The only real movement during the campaign so far has been a slight drop in Conservative support, from around 39% to about 37.5%, and a very small trend increase in support for the Lib Dems.