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What Is the ‘MRP Poll’ and Can It Predict the U.K. Election?

What Is the ‘MRP Poll’ and Can It Predict the U.K. Election?

(Bloomberg) --

On Wednesday evening at 10 p.m., YouGov will release details of the most eagerly awaited poll of the U.K. general election. Its so-called MRP poll will appear in the Times newspaper, predicting the result of the Dec. 12 vote, seat by seat. What is it, and why is there so much focus on it?

What is an MRP poll?

MRP stands for Multilevel Regression and Post-stratification. It’s a recently developed technique that aims to give a more detailed prediction than a standard opinion poll.

Why is there so much interest?

In the 2017 election, YouGov’s MRP poll predicted that Theresa May would lose her majority, at a time every other poll was suggesting her Conservatives would secure a big win.

How does it work?

By using a much larger sample than a standard poll -- around 50,000 people, rather than the usual 1,000 -- MRP aims to identify lots of different types of voters. Those might be high-earning finance workers who voted to leave the European Union, or university students who hate Brexit.

It works on the basis that these types of people tend to vote the same way when they live in similar places. Then the pollsters work out how many of each voter type there are in each constituency. Taking local factors into account, they predict the result for each of Great Britain’s 632 seats -- they don’t cover Northern Ireland -- in turn.

How reliable is it?

YouGov are keen to point out that it’s not magic. It takes a while to produce a poll like this, so it doesn’t reflect late swings in opinion. And MRP is only as good as the analysis: If YouGov get the wrong voter types, or fail to predict their behavior, it can still be wrong.

The 2017 poll actually underestimated Conservative performance. The poll itself can influence behavior: If it shows a race somewhere to be unexpectedly close, or not close at all, that could change the way the election campaigns are targeted, and could change the way people vote.

To contact the reporter on this story: Robert Hutton in London at rhutton1@bloomberg.net

To contact the editor responsible for this story: Tim Ross at tross54@bloomberg.net

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