Estimating National Results in Local Elections

England has a confusing patchwork quilt of local government. Local elections differ from year to year, in what types of councils are up for election, which party is defending councils, and where these councils are in the country. To overcome these issues, two separate teams of political scientists estimate what each party’s vote would have been had the whole country voted.

This article will discuss the BBC’s projected national share for local elections, and interpretations of the 2019 local election results.

Projected National Share

The BBC’s projected national share uses a sample of wards, estimating what vote share each principal party would have won under the conditions:

• Full candidature: the Conservatives, Labour and the Liberal Democrats fielded candidates in every ward;
• Nationwide: Every council was up for election across Great Britain.

This projected share is calculated by Prof Sir John Curtice and Prof Stephen Fisher for the BBC, and typically published the day after local elections have taken place. The aim is to compare local election results across years, rather than be limiting to only understanding each council cycle.

There are some limited differences between the BBC’s projected national share and the national equivalent vote share produced by Prof Colin Rallings and Prof Michael Thrasher, produced for the Sunday Times. The aim of the two estimates…