Template-type: ReDif-Paper 1.0
Author-Name: Peters Hans 
Author-Name: Roy Souvik 
Author-Name: Storcken Ton 
Author-workplace-name: METEOR
Title: On the manipulability of approval voting and related scoring rules
Abstract: We characterize all preference profiles at which the approval (voting) rule is manipulable, under three extensions of preferences to sets of alternatives: by comparison of worstalternatives, best alternatives, or by comparison based on stochastic dominance. We perform a similar exercise for $k$-approval rules, where voters approve of a fixed number $k$ of alternatives. These results can be used to compare ($k$-)approval rules with respect to their manipulability. Analytical results are obtained for the case of two voters, specifically, the values of $k$ for which the $k$-approval rule is minimally manipulable -- has the smallest number of manipulable preference profiles -- under the various preference extensions are determined. For the number of voters going to infinity, an asymptotic result is that the $k$-approval rule with $k$ around half the number of alternatives is minimally manipulable among all scoring rules. Further results are obtained by simulation and indicate that $k$-approval rules may improve on the approval rule as far as manipulability is concerned. 
Keywords: public economics ; 
Series: Research Memoranda
Creation-Date: 2009
Number: 060
File-URL: http://digitalarchive.maastrichtuniversity.nl/fedora/objects/guid:8c1e19ef-5876-4a8e-b069-e42439d6a0a7/datastreams/ASSET1/content
File-Format: application/pdf
File-Size: 495144
Handle: RePEc:unm:umamet:2009060