Why are political opinion polls getting it wrong more often? (1)

It is my contention that, across the democratic world, opinion pollsters are finding it harder to forecast accurately how political parties will do in elections and, on occasions, are getting the overall result wrong. Opinion polling is a complex matter and different companies use different methodologies, but all pollsters have the same problems of reaching the right people to construct a representative sample and of tracking short-term changes in voting intention.

The most dramatic recent case of poor polling in Britain was the General Election of May 2015 when the polls had Labour and Conservative neck-and-neck but in fact the Conservatives did significantly better than Labour. I have blogged about why the polls got it wrong on that occasion.

Essentially the problem was that some voters are easier to contact than others. Polling is becoming more difficult because fewer homes have a landline, many people do not like to answer unsolicited calls, not everyone is on the Net, volunteers for online polling are somewhat self-selecting, older people are less likely to be contacted by pollsters but more likely to vote, and those who are busy with work are less likely to be available but often more conservative.

The most recent international example of the pollsters getting it wrong was in last week’s General Election in Australia. All the polls forecast a Labour victory but the Liberal-National coalition was returned to power. What went wrong in the polling process? It is too soon to be sure but one pollster has already offered some reflections.

I was struck particularly the observation: “the polls were actually an accurate reflection of where the public was at the start of the week, and there was a move to the government in the final days of the campaign … We always knew there was a large cohort of voters with extremely light engagement.”

I think that what we are seeing is more voter fluidity. Class used to be the major determinant of voting behaviour and class does not change quickly, but class seems no longer to be the dominant factor that it was. Voters seem to be more willing to change support from election to election and even, in the course of the campaign, from week to week and day to day.

In a way, this is healthy for a democracy. It means that voters are thinking about their choices and willing to be influenced by the campaigns of the parties. But it can mean that voters are less engaged with politics and likely to be influenced by ephemeral factors.

What do you think?


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