Explaining the 2005 Coalition Formation Process in Germany: A Comparison of Power Index and Median Legislator Approaches

The article uses data from the 2005 German Bundestag elections to test the power index (PI) and median legislator (ML) models of coalition formation. The article finds that, while the PI approach is successful in predicting the real-world formation of a Grand Coalition after the election, neither model is sufficient to explain the outcome of the coalition formation process. Nevertheless, the article argues that such formal models are useful in identifying ‘crucial cases’ and in eliminating irrelevant data from explanations. The article concludes by suggesting some methodological routes through which formal models can be harnessed to culturally sensitive, inductive research.