The GroKo Effect: Does the Popularity of CDU/CSU and SPD Suffer from Grand Coalitions? Thomas Drechsel∗ London School of Economics This is work in progress. Please contact me if you have suggestions. April 4, 2018 Abstract This paper attempts to systematically assess the effect of government coalitions between the CDU/CSU and the SPD (\GroKos") on subsequent election outcomes of the two parties, using data on both federal and state elections in Germany over around 70 years. The key idea is to use the recurring presence of more than 30 of such coalitions at the state level to gain insight on their subsequent effects, exploiting the relative stability and homogeneity of the German party system across time and space. I show purely descriptively that the average change in vote shares after being the junior (senior) partner in a GroKo is -2.68 (-0.34) percentage points for the CDU/CSU and -2.58 (+0.85) percentage points for the SPD. This suggests a generally asymmetric effect between junior and senior coalition partners, and different effects between the two parties. A more formal statistical analysis, in which I control for other election and government characteristics as well as year and/or state fixed effects, reveals that junior (senior) partners consistently lose out (gain) after GroKos, and that the effects are stronger and statistically more significant for the SPD than for the CDU/CSU. ∗Department of Economics and Centre for Macroeconomics, London School of Economics. Houghton Street, London, WC2A 2AE, United Kingdom; E-Mail:
[email protected]; Web: http://personal.lse.ac.uk/drechsel/; For sharing some thoughts, I thank Miguel Bandeira, Kilian Huber, Jonathan Pinder and Guo Xu.