Publication detail

Turnovec F., Mercik J.W. and M. Mazurkiewicz (2008), Power Indices Methodology: Decisiveness, Pivots and Swings, in: Braham M. and F. Steffen, eds., “Power, Freedom and Voting”, Chapter 2, Springer Verlag, Berlin-Heidelberg, 23-37.

Author(s): † prof. RNDr. Ing. František Turnovec CSc., Mercik J.W., Mazurkiewicz M.
Type: Chapter in book
Year: 2008
Number: 0
ISSN / ISBN: ISBN 978-3-540-73381-2
Published in: Springer Verlag
Publishing place: Berlin-Heidelberg
Keywords: Absolute power, cooperative games, decisive situation, I-power, pivot, power indices, P-power, relative power, swing
JEL codes: D710, D740
Suggested Citation: Turnovec F., Mercik J.W., Mazurkiewicz M. (2008), Power Indices Methodology: Decisiveness, Pivotis and Swings. In: Power, Freedom and Voting (Braham. M. and Steffan F. eds.), Springer Verlag, Berlin-Heidelberg, 23-37.
Grants: IES Research Framework Institutional task (2005-2011) Integration of the Czech economy into European union and its development THE ECONOMICS OF DEMOCRATIC GOVERNANCE IN EXTENDING EUROPEAN UNION (program Kontakt 2006-12)
Abstract: Power indices methodology is widely used to measure an a priori voting power of members of a committee. In this paper we analyse Shapley-Shubik and Penrose-Banzhaf concepts of power measure and classification of so called I-power (voter’s potential influence over the outcome of voting) and P-power (expected relative share in a fixed prize available to the winning group of committee members). We show that objections against Shapley-Shubik power index, based on its interpretation as a P-power concept, are not sufficiently justified. Both Shapley-Shubik and Penrose-Banzhaf measure could be successfully derived as cooperative game values, and at the same time both of them can be interpreted as probabilities of being in some decisive position (pivot, swing) without using cooperative game theory at all. Moreover, both pivots and swings can be introduced as special cases of a more general concept of decisiveness based on assumption of equi-probable orderings expressing intensity of committee members’ support for voted issues. A new general a priori voting power measure is proposed distinguishing between absolute and relative power. This power measure covers Shapley-Shubik and Penrose-Banzhaf as its special cases.
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