Influence in Weighted Committees

TL;DR

This paper examines how various voting methods influence power distribution in weighted committees, using a generalized power index to analyze real-world decision-making bodies like the IMF.

Contribution

It introduces a generalized Penrose-Banzhaf power index for weighted committees and applies it to analyze influence in complex voting scenarios.

Findings

Different aggregation methods significantly affect influence distribution.

The generalized power index provides new insights into voting power dynamics.

Application to IMF shows practical relevance of the model.

Abstract

A committee's decisions on more than two alternatives much depend on the adopted voting method, and so does the distribution of power among the committee members. We investigate how different aggregation methods such as plurality runoff, Borda count, or Copeland rule map asymmetric numbers of seats, shares, voting weights, etc. to influence on outcomes when preferences vary. A generalization of the Penrose-Banzhaf power index is proposed and applied to the IMF Executive Board's election of a Managing Director, extending a priori voting power analysis from binary simple voting games to choice in weighted committees.