劳动供给为何对宏观经济学至关重要

中文摘要

本科宏观经济学课程所教授的基准模型并未将劳动供给视为宏观经济结果的重要决定因素。本文第一部分记录了三个事实。第一，OECD各经济体之间的工作时长差异很大，这意味着人均GDP存在巨大差异。第二，以政府收入占GDP比重的差异作为代理指标，各国税收与转移支付计划的规模存在巨大差异。第三，这两个结果呈强负相关。综合来看，这些事实表明劳动供给在影响宏观经济结果方面发挥着重要作用。本文推测，宏观经济学教科书之所以不讨论劳动供给，是因为人们相信劳动供给弹性足够小，以至于即便工作激励存在巨大差异，也不会产生重要的宏观经济影响。本文第二部分论证，这一看法源于一种错误推断，即把壮年男性较小的劳动供给弹性等同于总体劳动供给弹性也较小。劳动供给广延边际的作用，对于理解这一推断错误至关重要。

Abstract

Benchmark models taught in undergraduate macro do not attribute any role for labor supply as an important determinant of macroeconomic outcomes. The first part of this paper documents three facts. First, differences in hours of work across OECD economies are large and imply large differences in GDP per capita. Second, there are large differences in the size of tax and transfer programs across countries, as proxied by differences in government revenues relative to the GDP. Third, these two outcomes are strongly negatively correlated. Taken together, these facts suggest an important role for labor supply in affecting macroeconomic outcomes. I conjecture that the reason why macro textbooks do not include a discussion of labor supply stems from a belief that labor supply elasticities are sufficiently small that even large differences in work incentives do not generate important macroeconomic effects. The second part of this paper argues that this belief is based on incorrect inference linking small elasticities for prime age male to small aggregate labor supply elasticities. The role of labor supply at the extensive margin plays a critical role in understanding this mistake in this inference.