Macroeconomics and Inequality

无论是从人均财富还是从人均产出来看，美国都是世界上最富有的经济体之一，但它也是一个贫富差距非常大的经济体。这种不平等的根源是什么？经济学家和政策制定者是否应该对此感到担忧？这可能是成为世界上最富有的人的自然现象，甚至是必要的，还是反映了一种可以通过经济政策解决的失败？即使不平等本身不是一个令人担忧的问题，它是否会影响总体经济活动？虽然已经取得了很大的进展，但学院派经济学家还不能从数量上令人满意地解决上述问题。首先，很少有自然实验可以用纯粹的经验方法直接说明问题。其次，充分的经济理论基本缺失。这项研究解决了第二点：它旨在继续发展理论和数值工具，以定量研究不平等的来源及其与宏观经济学的相互关系。目前的项目，特别是，是一个早期项目的延续（NSF拨款#9807760），由该研究员与合作者。这项工作沿着几个方面进行，但共同的主题是开发和应用在宏观经济学和不平等的定量理论研究中普遍使用的方法。核心问题是一些相当基本的问题：是什么决定了不同的人在人力资本和物质资本方面的储蓄方式？技术变革如何影响工资不平等？经济政策如何影响不平等，又如何受到不平等的影响？该项目有特定的应用，但大部分工作都是关于相当广泛的适用性问题。子项目如下：1 .不平等的起源；a.储蓄：为什么家庭在储蓄倾向方面差异如此之大？这个项目继续了早期关于初始财富差异和劳动力市场运气的作用的研究，但也更进一步：是什么决定了“贴现因素”？这里的方法是心理学和经济学；心理学文献报告说，许多消费者似乎面临着消费的“冲动”，他们是否有，以及他们如何处理这种冲动，似乎差别很大。b.收入：体现在资本中的技术变革如何影响工资和人力资本不平等？可以说，目前和最近生产力的大部分改进都采取了这种形式，而关于这一主题的现有工作相当有限。本文的重点是劳动力市场的摩擦如何影响物质资本和人力资本的积累，以及经济政策如何与这些摩擦相互作用。2。不平等与总量之间的相互作用：a.财富分配对宏观经济有影响吗？本文对不平等——通过人口中储蓄和工作倾向的差异——影响总量的渠道进行了进一步调查。b.政策渠道：经济政策如何影响不平等，反之亦然？这项工作包括(i)对再分配和社会保险的政治经济研究和（ii）对决策者因缺乏承诺而受到限制时动态决策的研究。

The United States economy is one of the richest in the world, both in terms of per capita wealth and in terms of per capita output, but it is also an economy with very sharp contrasts between rich and poor. What is the source of this inequality, and should it concern economists and policy makers? Is it perhaps a natural, or even necessary, aspect of being the richest in the world, or does it reflect a failure that can be addressed with economic policy? And even if inequality per se is not a cause for concern, does it influence aggregate economic activity? Although much progress has been made, academic economists are not yet able to address the above issues in a quantitatively satisfactory way. First, few natural experiments are available to speak directly to the issues using purely empirical methods. Second, adequate economic theory is largely missing. This research addresses the second point: it aims to continue the development of the theory and numerical tools needed for a quantitative study of the sources of inequality and its interrelation with macroeconomics. The present project, in particular, is a continuation of an earlier project (NSF grant #9807760) by this investigator with collaborators. The work proceeds along several fronts, but the common theme is to both develop and apply methods that are of general use in quantitative-theoretical studies of macroeconomics and inequality. The central questions are rather basic ones: What determines how different people save, both in human and physical capital? How does technological change influence wage inequality? How does economic policy influence, and how is it influenced by, inequality? The project has specific applications, but most of the work is on questions of quite broad applicability. The subprojects are as follows: I. Origins of inequality: a. Savings: Why do households differ so much in their propensities to save? This project continues earlier work on the role of initial wealth differences and labor market luck, but also goes further: what determines "discount factors?" The approach here is one of psychology and economics; the psychology literature reports that many consumers seem to face "urges" to consume, and whether they do or not, and how they deal with the urges, seems to vary widely. b. Earnings: How are wage and human capital inequality influenced by technological change that is embodied in capital? Arguably, the bulk of the present and recent improve- ments in productivity take this form, and the existing work on the topic is quite limited. Here, the focus is on how frictions in the labor markets impact both accumulation of physical and human capital, and on how economic policy interacts with these frictions. II. Interactions between inequality and aggregates: a. Does the wealth distribution matter for macro? A further investigation of channels through which inequality-via the differences in propensities to save and work in the population-influences aggregates is undertaken here. b. The policy channel: How does economic policy affect inequality, and vice versa? This work includes (i) a political-economy study of redistribution and social insurance and (ii) a study of dynamic policy determination when policy makers are restricted by a lack of commitment.