Opinion pollster ‘house effects’ revealed in report

As party political attention focuses on the General Election – albeit with the likelihood of a by-election in Cambridgeshire South when Andrew Lansley is packed off to Brussels to be the UK’s contribution to the Commissioner Corps -the opinion polls will become increasingly important in telling us the possible outcome for May 2015.

The Political Betting blog reports that  the “Polling Observatory” at Manchester University have released their latest report in which they seek to estimate current electoral sentiment by pooling all the currently available polling data, while taking into account the estimated biases of the individual pollsters (“house effects”).  This allows them to assess whether the reported vote intention for a given pollster is above or below the industry average.

This is interesting as party supporters have their favourite pollsters, who they rate more highly than the others. For example, UKIP supporters love talking up Survation polls and many reject You Gov polls because Peter Kellner is married to the EU’s High Representative for Foreign Affairs and Security Policy, Baroness Catherine Ashton. Tories on the other hand prefer the results that Populus publish, while contending that Survation always understates the true level of Tory electoral support; and so on.

While the results are on the Manchester Uni page linked above, Political Betting’s love of Datawrapper has seen them plot the results on a party by party basis.  Makes interesting reading….

This becomes even more interesting when you look at these ‘house effects’ with the European Elections in mind, where we have already covered the accuracy of pollsters in light of the election results.

The issues seem to have their basis in both polling method (phone or internet) and adjustment methodology (how they deal with undecideds and those who won’t say who they plan to vote for).