Multiwinner Approval Voting: An Apportionment Approach

43 Pages Posted: 28 Mar 2017

See all articles by Steven J. Brams

Steven J. Brams

New York University (NYU) - Wilf Family Department of Politics

D. Marc Kilgour

Wilfrid Laurier University

Richard Potthoff

Duke University - Department of Political Science

Date Written: March 2017

Abstract

We extend approval voting so as to elect multiple candidates, who may be either individuals or members of a political party, in rough proportion to their approval in the electorate. We analyze two divisor methods of apportionment, first proposed by Jefferson and Webster, that iteratively depreciate the approval votes of voters who have one or more of their approved candidates already elected. We compare the usual sequential version of these methods with a nonsequential version, which is computationally complex but feasible for many elections. Whereas Webster apportionments tend to be more representative of the electorate than those of Jefferson, the latter, whose equally spaced vote thresholds for winning seats duplicate those of cumulative voting in 2-party elections, is even-handed or balanced.

Keywords: Approval Voting, Apportionment Methods, Multiple Winners, Proportional Representation, Cumulative Voting

JEL Classification: C63, C72, D63, D71, D72

Suggested Citation

Brams, Steven and Kilgour, D. Marc and Potthoff, Richard, Multiwinner Approval Voting: An Apportionment Approach (March 2017). Available at SSRN: https://ssrn.com/abstract=2940994 or http://dx.doi.org/10.2139/ssrn.2940994

Steven Brams (Contact Author)

New York University (NYU) - Wilf Family Department of Politics ( email )

Dept. of Politics
19 West 4th St., 2nd Fl.
New York, NY 10012
United States
212-998-8510 (Phone)
212-995-4184 (Fax)

HOME PAGE: http://politics.as.nyu.edu/object/stevenbrams.html

D. Marc Kilgour

Wilfrid Laurier University ( email )

75 University Ave W
Waterloo, Ontario N2L 3C5
Canada
519-884-0710 Ext.4208 (Phone)
519-884-5057 (Fax)

Richard Potthoff

Duke University - Department of Political Science ( email )

140 Science Drive (Gross Hall), 2nd floor
Duke University Mailcode: 90204
Durham, NC 27708-0204
United States

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