Partial Insurance and Consumption Inequality

本研究提案的主要目的是研究1980-1995年期间美国家庭消费分布的变化。这是一个有趣的研究时期，因为在劳动经济学文献中广泛分析了收入不平等的急剧增加。关于收入不平等加剧对福利的影响，存在一场公开辩论。一种观点认为，收入不平等的加剧令人担忧，因为这意味着生活水平的下降。另一种观点认为，人们更应该关注消费不平等，因为消费比收入更能衡量福利。该理论认为，家庭消费取决于永久收入，而不是当前收入，由于暂时的波动，这与前者不同。该理论的主要观点是，由于缺乏针对收入损失的正式保险市场，个人就会利用个人储蓄来“自我保险”，以抵御暂时的冲击。因此，如果收入不平等的扩大主要是由于暂时性因素造成的，那么收入不平等扩大的福利效应就没有原先想象的那么严重。近年来对收入不平等演变的广泛研究并没有与消费不平等的可比研究相提并论。现有的研究得出了截然不同的结论（一些论文发现消费不平等增加，而另一些论文发现很少或没有变化），或者很少尝试用理论解释实证结果。该项目由三部分组成。首先，它使用各种微观经济数据集来分析消费不平等的趋势，并将其与收入不平等的趋势进行对比，以解释为什么不同的论文对消费分布的主要事实得出了不同的结论，重点是定义问题和样本选择。其次，它提供的证据（已经在初步工作中得到）表明，在研究期间，消费不平等的增长速度比收入不平等的增长速度要慢。一种可能的解释是，大部分收入不平等的增加确实是暂时的（收入不稳定）。然而，劳动经济学研究得出的结论是，收入不稳定性和永久性收入不平等在利率期间以相似的速度增加。如果说有什么区别的话，那就是永久的不平等超过了暂时的不确定性。第三，它调查了另一种解释的经验有效性，即收入不平等的加剧（至少部分）是由永久性因素造成的，但除了个人储蓄之外，还存在针对收入冲击的“部分保险”。这种形式的保险通过各种渠道非正式地提供：社会和金融机构、家庭网络以及合理利用其他家庭选择变量。研究者提供了部分保险对收入冲击程度的估计，并评估了保险机会的可获得性如何随时间和不同技能群体而变化。实证分析将采用两个数据集，即消费者支出调查和收入动态的小组研究。

The main objective of this research proposal is to study the changes in the distribution of household consumption in the US over the 1980-1995 period. This is an interesting period to study due to the dramatic increase in income inequality widely analyzed in the labor economics literature. There is an open debate on the welfare implications of increasing income inequality. One view is that the increase in income inequality is worrying because it implies declining living standards. Another view is that one should rather focus on consumption inequality because consumption is a better measure of welfare than income. The theory suggests that household consumption depends on permanent, not current income, which differs from the former due to temporary fluctuations. The theory's main insight is that absent formal markets for insuring against income losses, individuals use personal savings to "self-insure" against temporary shocks. Thus, if the increase in income inequality is mostly due to temporary factors, the welfare effects of increasing income inequality are less serious than originally thought. The extensive research on the evolution of income inequality in recent years has not been paralleled by comparable research on consumption inequality. The existing research has reached contrasting conclusions (some papers find an increase in consumption inequality, while others find little or no change), or made little attempt to interpret the empirical findings using theory. The project consists of three parts. First, it uses a variety of microeconomic data sets to analyze trends in consumption inequality and contrast them with trends in income inequality in order to explain why different papers reach different conclusions about the main facts of the consumption distribution, focusing on definitional issues and sample selection. Second, it provides evidence (already available in preliminary work) that consumption inequality increases at a slower pace than income inequality over the period of study. One possible interpretation is that most of the increase in income inequality is indeed of temporary nature (income instability). However, labor economics studies have reached the conclusion that income instability and permanent income inequality have increased at similar rates over the period of interest. If anything, permanent inequality outpaces transitory uncertainty. Third, it investigates the empirical validity of an alternative interpretation, that the increase in income inequality is (at least partly) due to permanent factors but there exists "partial insurance" against income shocks over and above personal savings. This form of insurance is provided informally through a variety of channels: social and financial institutions, family network, and rational use of other family choice variables. The investigator provides estimates of the extent of partial insurance against income shocks and assesses how the availability of insurance opportunities changes over time and across skill groups. The empirical analysis will be conducted on two data sets, the Consumer Expenditure Survey and the Panel Study of Income Dynamics.