Working papers, Department of Economics, WU (Wirtschaftsuniversität Wien)
Theoretical vs. Empirical Power Indices: Do Preferences Matter?
(), Monika Mühlböck
(), Elisabeth Nindl
() and Wolf Heinrich Reuter
Abstract: This paper considers empirically whether preference-based
(empirical) power indices differ significantly from their preference-free
(theoretical) counterparts. Drawing on the to date most comprehensive
sample of EU Council votes (1993-2011), we use item-response models to
estimate the EU27 member states’ preferences (ideal points) in a
one-dimensional policy space. Their posterior distributions are then used
for the calculation of empirical versions of the Banzhaf, the
Shapley-Shubik, and other power indices, invoking the concepts of connected
coalitions and bloc voting. Our ideal point estimates point to significant
differences in member states’ preferences, which often translate into
significant differences of empirical (versus theoretical) power under
individual voting. However, the formation of voting blocs appears to offset
differences in countries’ ideal points as the bloc size grows.
Interestingly, this result does not hold up for the Shapley-Shubik index,
whose empirical variant differs from the theoretical one both under
individual and bloc voting.
Keywords: EU Council, Spatial Voting, Power Index; (follow links to similar papers)
JEL-Codes: D72,; C71,; C72; (follow links to similar papers)
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