Collaborative Research: The Dimensions of Supreme Court Decision Making, 1946-2000

什么因素最能解释美国最高法院法官的法律的决定？在裁决案件时，大法官的政策偏好在多大程度上超过了纯粹的形式上的、法律的关注？有多少政策维度构成了战后大法官的偏好？现在的最高法院比文森和早期的沃伦法院更保守吗？随着时间的推移，下级法院的判决是否变得更加自由？随着时间的推移，法院的政策产出发生了哪些变化？这些只是研究人员将使用针对美国最高法院特点定制的统计模型回答的一些实质性问题。更具体地说，使用贝叶斯推理方法，主要研究者开发了项目反应模型的变体：1）适用于受试者人数较少的多维选择情况; 2）在理想点和案例参数中明确建模动态; 3）可以用来解释具有协变量的投票行为（案例事实，起源法院，提出的论点，考虑的问题等）。同时控制和衡量政策偏好。为了模拟理想点和案例参数的动态，主要研究者在项目反应建模的背景下使用动态线性模型（DLM）机制。该提案的目标之一是整合这些建模策略，以便多维模型可以以计算高效的方式适合纵向数据。该提案的第二个方法目标是建立和拟合模型，共同衡量政策偏好，并考虑到衡量的协变量对投票决定的影响。该项目位于社会统计学中几个最近增长领域的交叉点：二进制时间序列和时间序列横截面数据分析，混合建模，分层贝叶斯建模和潜变量建模。虽然所提出的模型类别将针对涉及美国最高法院决策的工作进行定制，但许多所提出的方法将与政治学（如下级法院的行为，委员会决策和立法行为）和社会统计学的其他领域（如教育统计，心理计量学和计量经济学）的其他应用相关。

What factors best explain the legal decisions of U.S. Supreme Court justices? To what extent do the policy preferences of justices outweigh purely formal, legal concerns when deciding cases? How many policy dimensions structure the preferences of justices in the post-war era? Is the current Court more conservative than the Vinson and early Warren courts? Have the decisions of lower courts become more liberal over time? In what manner have the policy outputs of the Court changed over time? These are but a handful of the substantive questions the researchers will answer using statistical models customized to the peculiarities of the U.S. Supreme Court. More specifically, using a Bayesian inferential approach, the principal investigators develop variants of item response models that: 1) are suitable for multidimensional choice situations with small numbers of subjects; 2) explicitly model dynamics in ideal points and case-parameters; and 3) can be used to explain voting behavior with covariates (case facts, the court of origin, the arguments raised, the issues considered, etc.) while simultaneously controlling for and measuring policy preferences. To model the dynamics of ideal points and case parameters, the principal investigators use the dynamic linear model (DLM) machinery within the context of item response modeling. One of the goals of this proposal is to integrate these modeling strategies so that multidimensional models can be fit to longitudinal data in a computationally efficient manner. The second methodological goal of this proposal is to build and fit models that jointly measure policy preferences and account for the effects of measured covariates on voting decisions. This project lies at the intersection of several recent growth areas in social statistics: binary time-series and time-series cross-sectional data analysis, mixture modeling, hierarchical Bayesian modeling, and latent variable modeling. While the proposed class of models will be customized for work involving decision making on the U.S. Supreme Court, many of the proposed methods will be relevant to other applications in political science (such as behavior on lower courts, committee decision making, and legislative behavior) and other areas of social statistics (such as educational statistics, psychometrics, and econometrics).