Integrating and decomposing the sources of partisan bias: Brookes' method and the impact of redistricting in Great Britain

In a recent paper, Grofman et al. claimed that no method is available with which the partisan bias characteristic of single-member constituency electoral systems can be decomposed into the various bias-inducing factors. This note draws attention to a method that meets that criterion, and which was developed forty years ago. The method is described and illustrated, and used to assess the impact of recent redistrictings in Great Britain.