Replication Data for: Measuring Foreign Policy Positions of Members of the US Congress

Studies have shown that a foreign policy position of a member of Congress is often distinct from a domestic one. Despite this, measures commonly used to determine the foreign policy positions of members of Congress are based on congressional votes on domestic as well as foreign policy matters. Since foreign policy votes take up only a small portion of all congressional votes, these measures conflate a member’s foreign policy position with his or her domestic policy position. While there are other measures based exclusively on foreign policy votes, these are also problematic because they tend to use a small number of controversial votes and thus inflate extremism. To address these shortcomings, I present a new measure by applying a Bayesian item response theory model to all foreign policy votes. This paper demonstrates the similarities, differences, and advantages of this measure by comparing it with the existing measures in a series of analyses of foreign policy positions of political parties and individual legislators.

研究表明，美国国会议员的外交政策立场往往与其国内政策立场存在显著差异。尽管如此，当前用以研判国会议员外交政策立场的主流测度方法，却同时基于国会针对国内政策与外交政策的表决结果。由于外交政策表决仅占国会全部表决的极小比例，此类测度方法会将议员的外交政策立场与其国内政策立场混为一谈。尽管存在其他仅基于外交政策表决的测度方法，但这类方法同样存在缺陷：它们往往仅采用少量争议性表决样本，进而夸大了议员的极端主义倾向。为弥补上述缺陷，本文提出一种全新测度方法：将贝叶斯项目反应理论（Bayesian Item Response Theory）模型应用于全部外交政策表决数据。本文通过一系列针对政党与个体议员外交政策立场的分析，将该测度方法与现有同类方法进行对比，以此阐明二者的异同之处与本方法的优势所在。