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Paper

Bias and Responsiveness in Multiparty and Multigroup Representation Monroe, Burt L. Uploaded 07-21-1998 Keywords partisan bias responsiveness seats and votes electoral systems compositional data JudgeIt Abstract There is an extensive and expanding literature that examines methods for estimating the responsiveness and partisan bias of two-party electoral systems. Attempts to extend these methods into the multiparty domain appropriate for the vast majority of electoral systems, or to the analysis of the representation of other types of groups (e.g., regions, ethnic groups), have been limited. I describe index, multiyear, uniform swing, and variable swing methods -- along with novel graphical displays -- for analyzing seats-votes curves, bias, and responsiveness in multiparty systems. The variable swing method is a multiparty generalization of Gelman and King's "JudgeIt" model. Examples discussed include elections in the UK, Mauritius, and Costa Rica, and geographic representation worldwide. In comparing the various methods it is argued that variable swing is ideal for most applications, that uniform swing and index methods provide useful answers to a limited set of questions despite faulty assumptions, and that multiyear methods are generally not useful.