Most polls predict a healthy Labour majority, but there is still some variance in the size of that predicted lead.Most polls predict a healthy Labour majority, but there is still some variance in the size of that predicted lead.There have been polls, so many polls it is almost impossible to keep up with them. But they are all showing extraordinary“If the polls are right” seems to be the soundtrack to the campaign.
The British Polling Council found samples were to blame in 2015: the samples had too many Labour voters in them. This may sound obvious in a polling miss but there are ways for even a strong sample to go awry. The industry has worked hard to correct this, though there remain challenges among some groups – most notably younger men without a university degree.
Past voters are quite likely to vote again, so this poses a challenge for getting vote shares right. Broadly, there are two methods in use. The first is to exclude the undecided when calculating the final vote shares. This assumes undecided voters will eventually end up distributed across the parties in the same way as everyone else.