Proximity and linkages among coalition participants: a new voting power measure applied to the International Monetary Fund

Voting power methodology offers insights to understand coalition building in collective decision making. Using cooperative game theory, Banzhaf (1965) developed an index to capture the numerical importance of voters in coalition building. This voting power index is still widely used today in applications to international politics. Yet, it assumes that voters are symmetric and focuses on particular voters only. This paper proposes a new measure of voting power which account for the numerical proximity between voters by capturing how often they appear in winning coalitions together. The index is also developed to account for the relative importance of coalitions and the relative linkages among coalition participants. We present an application to the governance structure of the International Monetary Fund, with linkages being represented by bilateral trade between voters. The results are able to explain several important features of the functioning of this particular voting body, and may be useful for other applications of international politics. JEL Classification: C71, F33coalition building, International Monetary Fund, voting power

An axiomatic characterization of the Owen-Shapley spatial

We present an axiomatic characterization of the Owen-Shapley spatial power index for the case where issues are elements of two-dimensional space. This characterization employs a version of the transfer condition, which enables us to unravel a spatial game into spatial games connected to unanimity games. The other axioms are spatial versions of anonymity and dummy, and two conditions concerned particularly with the spatial positions of the players. We show that these axioms are logically independent

Analyse spatiale du pouvoir de vote : application au cas de l'intercommunalité dans le département du Val d'Oise

The spatial analysis of power indices is commonly used in the literature to study the importance of ideological criteria. Our purpose is to show, through the example of some french groupings of local cities, the importance of the geographical situation of the players when considering power analysis. We show that the classical measure of power (with the Shapley-Shubik index of power) may be sometimes radically different if the geographical aspect of the player is taken into account (with the Shapley-Owen index of power).Shapley-Shubik index of power, french grouping of local cities, spatial analysis

An axiomatic characterization of the Owen-Shapley spatial power index

We present an axiomatic characterization of the Owen-Shapley spatial power index for the case where issues are elements of two-dimensional space. This characterization employs a version of the transfer condition, which enables us to unravel a spatial game into spatial games connected to unanimity games. The other axioms include two conditions concerned particularly with the spatial positions of the players, besides spatial versions of anonymity and dummy. The last condition says that dummy players can be left out in a specific way without changing the power of the other players. We show that this condition can be weakened to requiring dummies to have zero power if we add a condition of positional continuity. We also show that the axioms in our characterization(s) are logically independent

Analyse spatiale du pouvoir de vote : application au cas de l’intercommunalité dans le département du Val d’Oise

L’analyse spatiale des indices de pouvoir est généralement employée dans la littérature afin d’étudier l’importance des critères idéologiques. Notre propos est ici de montrer, à travers l’exemple de structures intercommunales françaises, que la situation géographique des joueurs peut avoir un impact important en terme de pouvoir. En effet, prendre en compte la situation géographique (en utilisant l’indice de Shapley-Owen) change parfois radicalement les mesures usuelles du pouvoir (en utilisant l’indice de Shapley-Shubik).The spatial analysis of power indices is commonly used in the literature to study the importance of ideological criteria. Our purpose is to show, through the example of some French groupings of local cities, the importance of the geographical situation of the players when considering power analysis. We show that the classical measure of power (with the Shapley-Shubik index of power) may be sometimes radically different if the geographical aspect of the player is taken into account (with the Shapley-Owen index of power)