Leech, Dennis (2002) The use of Coleman's power indices to inform the choice of voting rule with reference to the IMF governing body and the EU Council of Ministers. Working Paper. Coventry: University of Warwick, Department of Economics. (Warwick economic research papers).

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Abstract

In his well known 1971 paper the mathematical sociologist James S. Coleman, proposed three measures of voting power: (1) "the power of a collectivity to act", (2) "the power to prevent action" and (3) "the power to initiate action". (1) is a measure of the overall decisiveness of a voting body taking into account its size, decision rule and the weights of its members, while (2) and (3) are separate indices of the power of individual members, in being able to block or achieve decisions. These measures seem to have been little used for a variety of reasons, although the paper itself is widely cited. First, much of the power indices literature has focused on normalised indices which gives no role to (1) and means that (2) and (3) are identical. Second, Coleman's coalition model is different from that of Shapley and Shubik which has sometimes tended to dominate in discussions of voting power. Third, (2) and (3) are indistinguishable when the decision quota is a simple majority, the distinction becoming important in other voting situations. In this paper I propose that these indices, which are based on a fundamentally different notion of power than that assumed by game-theoretic approaches, have a useful role in aiding a better understanding of collective institutions in which decisions are taken by voting. I use them to illustrate different aspects of the design of a weighted voting system such as the governing body of the IMF or World Bank, or the system of QMV in the European Council.

Item Type:	Working or Discussion Paper (Working Paper)
Subjects:	H Social Sciences > HM Sociology
Divisions:	Faculty of Social Sciences > Economics
Library of Congress Subject Headings (LCSH):	Coleman, James Samuel, 1926-1995, Council of the European Union, International Monetary Fund. Executive Board, Rational choice theory, Voting research, Decision making, Mathematical sociology
Series Name:	Warwick economic research papers
Publisher:	University of Warwick, Department of Economics
Place of Publication:	Coventry
Date:	July 2002
Number:	No.645
Number of Pages:	25
Status:	Not Peer Reviewed
Access rights to Published version:	Open Access
Description:	Paper prepared for the workshop "Modelling the European Decision Making", San Sebastian, Spain, July 12-14
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URI:	http://wrap.warwick.ac.uk/id/eprint/1541

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