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MRP Estimates and the 2019 General Election
What is multi-level regression with post-stratification?
MRP stands for ‘multi-level regression with post-stratification’. It is a statistical technique used to transform national opinion survey results into local estimates.
This article examines the technique and what can go wrong, particularly focused on its use prior to the 2019 UK General Election.
What is MRP?
MRP is a technique for building a model of public opinion. It is not the model itself. The underlying assumption is that similar types of people have similar views, such as vote intention, across the country.
These models have been become popular among survey researchers and political scientists, performing better than national survey sub-samples for each constituency.
The model seeks to estimate a person’s political opinion such as how they intend to vote, by their demography and constituency. By using the census, we can add up what kinds of people there are in each constituency, giving an estimate of vote intention for that constituency.
This technique is not perfect. However, MRP offers a good way of estimating local opinions where full, separate surveys would be impractical or too expensive, such as all constituencies in the House of Commons.
There is a step-by-step process for building such a model.
