How to Operationalize Two-Partyness

Brian J. Gaines, Rein Taagepera

Research output: Contribution to journalArticlepeer-review


Because of the prominence of Duverger's law, a great deal of work has focused on assessing whether or not given election outcomes can be regarded as exhibiting two-party competition. The most common metric for assessment is whether the effective number of parties is close to two. We introduce two statistics that better measure conformity to two-partyness, briefly survey their logical properties, and then demonstrate their utility with data on parliamentary elections in England.

Original languageEnglish (US)
Pages (from-to)387-404
Number of pages18
JournalJournal of Elections, Public Opinion and Parties
Issue number4
StatePublished - Nov 2013

ASJC Scopus subject areas

  • Sociology and Political Science


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