From Population Growth to Firm Demographics: Implications for Concentration, Entrepreneurship and the Labor Share
Econometrica · 2022 · Hugo A. Hopenhayn、Julian Neira、Rish Singhania
中文摘要
在美国，大企业目前占经济活动的份额更大，新企业创建的速度放缓，劳动者获得的GDP份额下降。人口增长的变化为这些现象提供了一个统一的定量解释。人口增长下降会降低企业进入率，使企业年龄分布向更老的企业移动。企业老化可以解释： 就业向大企业集中，以及 平均企业规模和退出率（企业进入率的关键决定因素）的趋势。来自企业人口结构的反馈效应贡献了其中的三分之二。在人口增长下降之前，进入率持续上升，反映了此前的婴儿潮。婴儿潮导致的企业过剩在反馈效应内部产生了丰富的转型动态，占总变化的超过一半。婴儿潮所引发的企业年龄分布变化，为二战后总劳动收入份额的先升后降提供了驱动力。若忽视人口增长的变化，则会把进入率的全部长期下降归因于企业退出率的下降，而后者在现实中仅为前者的三分之一。
Abstract
In the U.S., large firms now account for a greater share of economic activity, new firms are being created at slower rates, and workers are receiving a smaller share of GDP. Changes in population growth provide a unified quantitative explanation. A decrease in population growth lowers firm entry rates, shifting the firm‐age distribution toward older firms. Firm aging accounts for (i) the concentration of employment in large firms, (ii) and trends in average firm size and exit rates, key determinants of firm entry rates. Feedback effects from firm demographics generate two‐thirds of the effect. Prior to the decrease, entry rates rose steadily reflecting the earlier baby boom. The glut of firms due to the baby boom lead to rich transitional dynamics within the feedback effects, accounting for more than half the total change. Baby boom induced changes in the firm‐age distribution provide a driving force for the post‐WWII rise and fall in the aggregate labor share. Ignoring changes in population growth attributes all the long run decline in entry rates to a decrease in firm exit rates, which in reality have been only one‐third as large.