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Paper

A method for measuring and decomposing electoral bias for the three-party case Borisyuk, Galina Johnston, Ron Rallings, Colin Thrasher, Michael Uploaded 03-26-2008 Keywords electoral bias decomposition of bias British parliamentary elections Abstract The paper provides a method for measuring and decomposing electoral bias for the three-party case. It builds on the two-party method first developed by Ralph Brookes in the late 1950s. Modifications to the original Brookes method developed in the early 1990s were designed to capture the third party effect in the overall distribution of bias but that bias continued to be expressed in terms of the two major parties. Recent general election results in Britain continue to show strong voter support for the third party. This new method specifically considers the three party situation and calculates both overall bias and also its decomposition at the 2005 general election. The results from this new method are then compared with those found by the Brookes method for each election held since 1983.