Publication detail

Fair Majorities in Proportional Voting

Author(s): † prof. RNDr. Ing. František Turnovec CSc.,
Type: Articles in journals with impact factor
Year: 2013
Number: 3
ISSN / ISBN: ISSN 0023-5954
Published in: Kybernetika, vol. 49 (2013), No. 3, pp. 498-505 (IF 0.619)
Publishing place: Praha ÚTIA
Keywords: fair majority, power indices, quota interval of stable power, simple weighted committee, voting power.
JEL codes: AMS Classification: 91A12, 91A40, 05C65
Suggested Citation: Turnovec F., Fair Majorities in Proportional Voting, Kybernetika, vol. 49, No. 3, pp. 498-505
Grants: GACR 402/09/1066: Political Economy of Voting Behavior: Rational Voter Theory and Models of Strategic Voting
Abstract: In parliaments elected by proportional systems the seats are allocated to the elected political parties roughly proportionally to the shares of votes for the party lists. Assuming that members of the
parliament representing the same party are voting together, it has sense to require that distribution of the influence of the parties in parliamentary decision making is proportional to the distribution of
seats. There exist measures (so called voting power indices) reflecting an ability of each party to influence outcome of voting. Power indices are functions of distribution of seats and voting quota (where voting quota means a minimal number of votes required to pass a proposal). By a fair voting rule we
call such a quota that leads to proportionality of influence to relative representation. Usually simple majority is not a fair voting rule. That is the reason why so called qualified or constitutional majority is being used in voting about important issues requiring higher level of consensus. Qualified majority is usually fixed (60% or 66.67%) independently on the structure of political representation. In the paper we use game-theoretical model of voting to find a quota that defines the fair voting rule as a function of the structure of political representation. Such a quota we call a fair majority. Fair majorities can differ for different structures of the parliament. Concept of a fair majority is illustrated on the data for the Lower House of the Czech Parliament elected in 2010.
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