General election polling goes geographical: the accuracy and value of constituency-level estimates

The 2017 general election saw a largely unremarked geographical extension to opinion polling, with three analysts publishing estimates of which party was likely to win in each of the country's constituencies. Ron Johnston, Kelvyn Jones, David Manley, Charles Pattie, Todd Hartman, and David Rossiter have analysed their accuracy and considered the implications of that development for the conduct of future elections.