Coalitions & Voting Power in the Greek Parliament of 2012: A Case-Study

TL;DR

This study analyzes voting power and coalition dynamics in the 2012 Greek Parliament elections using power indices, providing insights into institutional influence and electoral system reforms.

Contribution

It applies multiple power indices to model Greek parliamentary voting, offering empirical evaluation of their effectiveness in multi-party coalition contexts.

Findings

Power indices reveal influence disparities among parties.

Institutional rules significantly affect power distribution.

Empirical evidence on index performance in multi-party settings.

Abstract

We revisit the May and June 2012 Greek Parliamentary elections and the December 2014 Presidential election that was held by the June-elected Parliament. The three voting instances provide a political field experiment for the application of power indices and their interpretation in context. We model the Greek Parliament as a weighted majority game and assess voting power with the Shapley-Shubik, Holler and when relevant, Coleman's indices. Also, based on the actual events, we establish connections between parties and evaluate the Myerson index. We focus on the influence of institutional rules on the distribution of power among the elected political parties and add an alternative input to the ongoing political debate about the reform of both the Parliamentary and Presidential electoral system in Greece. Additionally, our findings contribute to the understanding of the coalition formation process in the particular context and provide empirical evidence on the performance of non-selective indices in parliamentary multi-party settings which can be used for comparison by similar case-studies in the future.