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Ulrich Sieberer, "Using MP statements to explain MP voting behaviour in the German Bundestag: An induvidual level test of the Competing Priciples Theory" Party Politics, 21 (March 2015), 284-294. [Available at]

First paragraph:

One key challenge for legislative research in parliamentary democracies is explaining why members of parliament (MPs) vote with or against their party. Various studies have explained party unity as the aggregate result of self-interested behaviour of MPs (e.g.Carey, 20072009Depauw and Martin, 2009Kam, 2009Saalfeld, 1995Sieberer, 2006,2010). The most prominent recent rational choice model of party unity – John Carey’s Competing Principals Theory (CPT) – uses a principal–agent model to explain dissenting votes based on the behaviour of MPs facing cross-pressure from more than one principal. While the theory has been quite successful in explaining cross-country and cross-party differences in unity, there have been few attempts to test its causal mechanisms on the level of individual MPs, mostly because MPs’ decision calculus cannot be studied solely based on roll-call voting behaviour.

Figures and Table

Table 1: Ideal typical scenarios of cross-pressure and strength of competing priciples and their consequeces for the usage and types of EoVs
Table 2: Estimation results for multi-level multinominal logit regression models with sample selection

Last Paragraph:

My findings open up three perspectives for future research on EoVs and similar statements. First, the analysis of this article should be extended over time to see whether the results, especially on the unexpected differences between the two cabinet parties, are caused by the special conditions of the Grand Coalition cabinet or reflect systematic variation between the party holding the chancellorship and junior coalition partners. Comparing the results in this article with earlier findings (Becher and Sieberer, 2008) leads me to expect that the effects of government status and leadership positions hold over time, while the electoral system effect may vary. Second, future analyses could study the arguments used in EoVs searching for references to competing principals and the strategies MPs use to balance between contradictory demands in their pursuit of re-election and career advancement. Finally, instruments similar to EoVs in other parliaments (for example in Belgium, The Netherlands and Italy) open up the potential for comparatively studying the determinants of individual voting behaviour and aggregate party unity in parliaments using the additional leverage provided by this new data source.

Last updated March 2015