A Complete Information Index for Measuring the Proportionality of Electoral Systems

Posted: 8 Nov 2004

See all articles by Ram Mudambi

Ram Mudambi

Temple University - Department of Strategic Management

Abstract

A crucial property of an electoral system is the manner in which it translates a vote distribution into a pattern of representation. Measures of this property are important in assessing the relative merits of differing electoral systems. I argue that indices that do not use the vote and seat shares of all competing parties are informationally incomplete. In this paper, a complete information index is developed and shown to have several desirable properties: (a) it is bounded between zero and unity; (b) it takes the value of unity in the limiting case of perfect proportionality; and (c) it takes the value of zero in the limiting case where the seat distribution is unaffected of the vote distribution. The index is shown to perform better than limited information indices in an illustration using data from Sicilian provincial elections.

Keywords: electoral systems, proportionality, measurement issues

JEL Classification: D72, D70, D79

Suggested Citation

Mudambi, Ram, A Complete Information Index for Measuring the Proportionality of Electoral Systems. Available at SSRN: https://ssrn.com/abstract=616081

Ram Mudambi (Contact Author)

Temple University - Department of Strategic Management ( email )

Fox School of Business and Management
Philadelphia, PA 19122
United States
215-204-2099 (Phone)
215-204-8029 (Fax)

HOME PAGE: http://sbm.temple.edu/~rmudambi/index.html

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