Welfare Analysis of Legislative Redistricting

最近最高法院的案件涉及种族和党派的不公正划分，加剧了全国对立法重新划分的辩论。然而，在这场辩论中，对于如何从促进选民利益的角度评估替代性选区重划计划，几乎没有达成一致意见。在最基本的层面上，相关的问题是：立法机构应如何代表不同的选民群体，以及选民应如何跨地区分配，以执行这一规定？本研究以传统的福利经济学为基础，从理论和实证的角度探讨这一问题及相关问题。作为一个规范性的基准，主要研究者开始研究意识形态团体应该如何在立法机构中代表。关键的发现是，席位-选票曲线，这与左翼政党所占席位的比例，其全国支持，应该是线性的，有一个积极的斜率，并偏向于占主导地位的政党。然后，他们研究如何在各区之间分配选民，以实现这一最佳的席位-选票曲线。这里的主要发现是，如果最佳的席位-选票曲线可以实施，那么地区应该是异质的，在他们的分配选民的意识形态和一些地区应该是“安全席位”。最后，该项目将制定实施最佳席位-选票曲线的条件，然后解决在这些条件不满足时如何在各区分配选民的难题。研究小组还将开发一个综合的理论和实证方法，从这个福利的角度来评估立法重新划分。它首先开发了一种方法来估计席位-选票曲线;这种方法只需要在立法选举中逐区支持左翼党的数据。然后，研究人员证明，选民福利可以直接测量这个观察到的席位-选票曲线以及任何其他可能的席位-选票曲线。因此，观察到的选民福利可以与选民福利下的最佳席位-选票曲线，允许测量任何福利损失次优重划。此外，观察到的选民福利可以与比例代表制下的选民福利进行比较，比例代表制是其他国家普遍使用的另一种投票制度。该方法还允许比较选民福利下的替代选区划分制度，包括两党，党派和独立委员会。最后，这些想法说明在美国州议会选举投票的应用。第三个项目旨在将前两个部分中提出的想法归纳为一个框架，在这个框架中，选民和候选人都由他们的意识形态和种族来定义。这一概括性的框架将被用来解决几个规范性的问题，有关种族重新划分。例如，黑人选民应该如何在立法机构中得到代表，如何在各区之间分配？虽然黑人占多数的地区倾向于选举黑人候选人，但他们也集中了自由派选民，这可能导致左翼候选人在其他地区的失败。因此，我们计划研究种族和意识形态之间的这种和其他潜在的有趣的相互作用。

Recent Supreme Court cases involving both racial and partisan gerrymandering have intensified a national debate over legislative redistricting. There is little agreement, however, in this debate over how alternative redistricting plans should be evaluated from the perspective of promoting the interests of voters. At its most fundamental level, the relevant question is: how should legislatures represent different groups of voters, and how should voters be allocated across districts in order to implement this prescription? This project develops an approach based upon traditional welfare economics in order to address this question and related questions from both a theoretical and empirical perspective. As a normative benchmark, the principal investigators begin by examining how ideological groups should be represented in legislatures. The key findings are that the seats-votes curve, which relates the fraction of seats held by the leftist party to its national support, should be linear, have a positive slope, and be biased in favor of the dominant party. They then examine how voters should be allocated across districts in order to implement this optimal seats-votes curve. The key findings here are that, if the optimal seats-votes curve can be implemented, then districts should be heterogeneous in their allocation of voter ideologies and that some districts should be "safe seats". Finally, the project will develop conditions under which the optimal seats-votes curve can be implemented and then tackle the difficult question of how voters should be allocated across districts when these conditions are not satisfied. The research team will also develop an integrated theoretical and empirical approach to evaluating legislative redistricting from this welfare perspective. It first develops a methodology for estimating seats-votes curves; this methodology requires only data on district-by-district support for the leftist party in legislative elections. The researchers then demonstrate that voter welfare can be directly measured for this observed seats-votes curve as well as for any other possible seats-votes curve. Thus, observed voter welfare can be compared with voter welfare under the optimal seats-votes curve, permitting measurement of any welfare losses from sub-optimal redistricting. In addition, observed voter welfare can be compared with voter welfare under proportional representation, an alternative voting system commonly used in other countries. The methodology also permits a comparison of voter welfare under alternative redistricting regimes, including bipartisan, partisan, and independent commissions. Finally, these ideas are illustrated in an application to voting in U.S. state legislative elections. The third project aims to generalize the ideas developed in the first two parts to a framework in which both voters and candidates are defined by their ideology as well as by their race. This generalized framework will be used address several normative questions related to race in redistricting. For example, how should black voters be represented in legislatures and allocated across districts? While black majority districts tend to elect black candidates, they also concentrate liberal voters, potentially leading to the defeat of leftist candidates in other districts. Thus, we plan to examine this and other potentially interesting interactions between race and ideology.