Yahoo News What is an exit poll? How the UK will get first hint of election results
People will get a good idea of how the UK voted shortly after the polls close on 4 July thanks to an exit poll.
Just after 10pm on July 4 when the polls close in the UK, British people will get their first idea of the election results, in advance of the actual final count, with an exit poll.
The exit poll is conducted by experts from polling companies used by the UK's major broadcasters, with pollsters asking a sample of voters about their choices immediately after they have cast their ballots, and then extrapolating this to work out what the overall result might be.
Although exit poll results come in during the day, it’s illegal to release these results until polling stations close at 10pm on Thursday, 4 July. The results of exit polls tend to be significantly more accurate than opinion polling during the election process.
Before the results for individual constituencies come in throughout the night, the 10pm exit poll offers an insight into what is likely to happen.
What is an exit poll?
Exit polls have been used internationally since at least the late 1960s, with pollsters asking voters their intention as they leave the polling booth.
The exit poll in the UK covers England, Scotland and Wales (in Northern Ireland, voters choose from a different set of parties).
Polling companies use teams of statistics experts to make sense of the data from exit polls in more than 100 constituencies and thousands of voters.
How do exit polls work?
Pollsters visit a selected polling station in a constituency and ask selected voters to fill in a replica ballot paper after they have filled in their real one.
The idea of this is that people tend to be more honest while writing down their vote than saying it out loud.
The experts compare data on the day to previous elections, looking for changes in voting behaviour.
The experts take the small samples from polling stations and analyse this to find broader geographic trends in how people are voting - for example, whether there is a swing towards Labour in the north of England.
Statistical analysis allows experts (teams of highly respected academic statisticians led by pollster Professor Sir John Curtice) to come up with a projected figure of how many seats each party will get.
How accurate are exit polls?
Generally speaking, exit polls in the UK have become more accurate over time, as the techniques used have improved.
Exit polls offer an often accurate depiction of what might happen in the real election. For example, in 2019, the exit poll forecast 368 for Conservatives and 191 for Labour, and the real figure was 365 and 203 seats.
Professor Sir John Curtice, who leads Britain’s exit polling team, says that the results offer a ‘pretty good indication’ of the real result.
But with Britain’s political landscape shifting, polls can sometimes fail - in 2015, the exit poll predicted a hung parliament rather than a Conservative majority.
This year’s exit poll will take into account data including how constituencies voted in the 2016 referendum.
Famously in 1992, exit polls for the BBC forecast a hung parliament, but the Conservatives won 65 more seats than Labour with a majority of 21 seats – although the statistical techniques used in exit polling have evolved significantly since then.
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