Populus and Survation had almost the same raw figures for UKIP support yet their headline numbers were very different
The impact of different polling methodologies
Both Populus and Survation operate in a very similar manner. Both do their fieldwork online, both weight for likely turnout, and both apply a formula to ensure that their samples are politically balanced.
Survation uses past voting weighting comparing what respondents said they did at GE2015 and with the actual result.
Populus asks “which political party would you say you have usually most closely identified yourself with?” and compares back to the 2010 Social Attitudes Survey.
The outcome in their latest poll is very different as the chart shows. Compressing UKIP produces larget figures for the other main parties.
Mike Smithson
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