How six became four at Populus

A new dimension in UK opinion polls was introduced yesterday that could have a major impact for all political gamblers.

The front page of the Times was dominated with news of the latest Populus Poll that showed the Tories 4% ahead. There was only one problem – the actual lead was 6% but in a feature on the inside pages was news that Populus had introduced a new policy – to compensate in favour of Labour.

They say the move has been made necessary because interviewees are now reluctant to admit they are Labour supporters. We will have to wait until after the General Election to find out whether this proposition is correct.

For political gamblers betting on the General Election markets this starts to get onto very dangerous territory. For a 6% lead is just one point below the critical level of 7% – the point at which the Conservatives will win more seats than Labour on a uniform national swing and the basis of many General Election bets.
We are not saying that Populus is right or wrong – the General Election results will show that – but it is vital for gamblers to be aware of how figures are produced. Even with the new policy the odds on a Tory victory continue to shorten.

For many years the pollsters have been trying to find a way of compensating in favour of the Conservatives following a series of disasters caused by over-estimating Labour support and under-estimating the Conservatives. Even 2001 saw one opinion poll after another reporting large Labour leads of upto 28% when the actual result was Labour just 9.3% ahead.

The problem was caused, as we have discussed here before, by interviewees being reluctant to admit they were Tories. A reason why internet polls give higher Conservative totals, it’s argued, is that the person being polled is not responding to a human being but a machine.

It is interesting that in the latest round of polls the internet pollster, YouGov is showing substantially higher figures for both Labour and the Conservatives. Could it be that the only people happy to admit their political allegiances are Liberal Democrats?

In explaining the policy Andrew Cooper of Populus wrote this:-

Early last year, after a short period of neutrality, the spiral of silence reversed itself. Polls began to find that the proportion of former Labour voters saying that they didn’t know how they would vote next time began to climb, while the proportion of Labour supporters saying that they were sure to vote began to fall. Pollsters have been adjusting Labour’s poll support upwards to take account of this growing number because all empirical data tell us there is about a 60 per cent probability that, however reluctantly, if they vote at all they will end up voting Labour again. Without this adjustment the Conservative lead in today’s poll would have been 2 per cent higher. SO in place of Shy Tories we now have Bashful Blairites, people unwilling to admit to pollsters or their friends that they still support the Prime Minister. Once so fashionable, new Labour has now gone out of fashion. This is very difficult to reverse.

Cooper says his evidence is empirical – the real test will come at the General Election.