Replication data for: Gubernatorial and Presidential Coattails in Brazil

In ‘Understanding Interaction Models: Improving Empirical Analyses’, we report the results of several replications that we conducted of analyses examining electoral institutions and party systems. One of these replications was of David Samuels’ article ‘The Gubernatorial Coattails Effect: Federalism and Congressional Elections in Brazil’ which appeared in the Journal of Politics in 2000. In an article in the Journal of Politics, Samuels (2000) examines the relative impact of presidential and gubernatorial coattails on the composition of the Brazilian party system. Theory would suggest that temporally-proximate presidential and gubernatorial elections should exert a reductive effect on the number of electoral lists in legislative elections. However, this reductive effect should decline (and may become positive) as the number of presidential and gubernatorial candidates increases. Samuels argues that the unusual importance of the governor for office-seeking candidates in Brazilian legislative elections means that we should observe a gubernatorial coattails effect but not a presidential coattails effect in Brazil. This would help to explain why the party system at the national level is highly fragmented (6.3 effective parties), while the party system at the state level is more concentrated (only 3.3 effective parties). The results from three models seem to support his conjecture. However, Samuels draws conclusions from an interaction model that omits constitutive terms. Once these omitted terms are included, none of the coefficients on the variables of interest are significant at the 90% level. Plots of the marginal effect of gubernatorial elections on the number of electoral lists across the observed range of the modifying variable from all three models indicate that gubernatorial elections never exert a coattails effect. While two of the three models indicate that there is no presidential coattai ls effect either, one suggests that temporally-proximate presidential elections will increase the number of electoral lists if the number of presidential candidates is sufficiently high. Thus, contrary to the conclusions reached by Samuels, the evidence from a fully-specified model indicates that if there is a coattails effect in Brazilian elections then it is a presidential one and not a gubernatorial one. This indicates that gubernatorial coattails cannot explain why the state party system in Brazil is so much less fragmented than the national party system.

在《理解交互模型：改进实证分析》（*Understanding Interaction Models: Improving Empirical Analyses*）一文中，我们报告了多项针对选举制度与政党体系开展的分析的重复研究结果。其中一项重复研究针对的是大卫·塞缪尔斯（David Samuels）2000年发表于《政治学杂志》（*Journal of Politics*）的论文《州长连带选票效应：巴西的联邦制与国会选举》（*The Gubernatorial Coattails Effect: Federalism and Congressional Elections in Brazil*）。塞缪尔斯（2000）在该文中探讨了总统与州长连带选票效应对巴西政党体系构成的相对影响。理论层面的推论认为，时间上邻近的总统与州长选举，应对立法选举中的参选政党名单数量产生缩减效应。不过，随着总统与州长候选人人数的增加，这种缩减效应应当会减弱，甚至可能转为正向影响。塞缪尔斯提出，在巴西的立法选举中，州长对于寻求公职的候选人而言具有非同寻常的重要性，因此我们应当观察到州长连带选票效应，而非总统连带选票效应。这一推论或可解释为何巴西全国层面的政党体系高度碎片化（有效政党数为6.3），而州层面的政党体系则更为集中（仅3.3个有效政党）。三项模型的结果似乎印证了他的猜想。但塞缪尔斯的结论基于一个遗漏了构造型项的交互模型。当纳入这些被遗漏的构造型项后，所有关注变量的系数在90%的置信水平上均不再显著。通过绘制所有三项模型中，在调节变量的观测取值范围内，州长选举对参选政党名单数量的边际效应图，可以发现州长选举从未产生连带选票效应。尽管三项模型中有两项同样表明不存在总统连带选票效应，但其中一项模型显示，若总统候选人人数足够多，时间上邻近的总统选举将会增加参选政党名单的数量。因此，与塞缪尔斯的结论相悖，基于完全设定模型的实证结果表明：若巴西选举中存在连带选票效应，那也应当是总统连带效应，而非州长连带效应。这意味着州长连带选票效应无法解释巴西州级政党体系为何比国家级政党体系碎片化程度低得多。