NEWS26 May 2017

BPC details how pollsters have changed methodology

Brexit News UK UK General Election

UK – The British Polling Council (BPC) president, John Curtice, has outlined how the different polling companies have changed their polling methods in light of their poor performance in the 2015 general election.

Voting vote election_crop

“On average the final polls (that is, those whose fieldwork concluded no more than two days before polling day) put the Conservatives and Labour equal on 34%, when, in practice, the Conservatives proved to be on 38% and Labour on 31%,” he said.

After the election the BPC and MRS set up an independent inquiry led by Professor Patrick Sturgis looking into why the inaccuracies happened. The BPC members have since acted on the report’s recommendations.

“Even so, many people are inevitably still asking whether the polls have learnt from what happened in 2015 and can be relied upon to provide a more accurate estimate of Conservative and Labour support in the 2017 election,” said Curtice.

He pointed out that each company has responded to the lessons of the 2015 election in its own way. “No two companies are conducting their polls in exactly the same way, however two general themes emerge,” he said.

First, most companies have implemented one or more changes designed to improve their estimates of which voters are likely to make it to the polls and which not. For example by ensuring more potential non-voters are interviewed in the first place.

Second, often companies have made changes to ensure the political balance among those who will make it to the polls is estimated accurately. For example by greater use of weighting the data by how people voted in the 2015 election, and that the data also reflects how people voted in the EU referendum.

Details of the methodological changes made by individual companies can be found here