Growth and Cycles

这个项目的目标是开发一种模式，在这种模式下，有动力采用一种新技术，因为它可以提高生产率，但新技术可能需要对人力资本水平进行大幅调整。该模型将被用来解释增长的波动性、增长率灾难、逆周期人力资本积累以及其他关于经济增长的经验观察。实际经济周期研究是关于经济周期、经济增长和技术冲击之间关系的大量且非常有用的文献。但几乎所有这些研究都假设技术冲击是外生的，并研究经济如何应对它们。该项目开发了一种模式，在这种模式下，技术被选择，全要素生产率取决于当前的技术和人力资本，人力资本可以以成本的方式升级，以更好地匹配未来的技术。在这种模式下，采用技术是有风险的。风险之一是可能拥有错误的技能，因此承担重装的巨额成本，并存在额外的风险。因此，选择一种更好的技术直接提高了未来的生产率，但也增加了必须花费资源来升级人力资本以跟上步伐的风险。如果增长带来风险，那么我们似乎应该观察到增长率与其波动性之间的正向关系。然而，数据显示，随着时间的推移，两者之间存在负相关关系。这个项目开发了一个模型来解释这一点，因为更高的波动性会导致未来技术和技能之间更大的不匹配，以及更高的重组成本。该模型可以分散和扩展，以便符合战后美国数据和其他地方观察到的产出、消费、投资、股票价格和利率增长率的分布。商业周期在一定程度上是技术选择的结果。该项目研究政策影响如何取决于技术使用和人力资本调整的外部影响。

The goal of this project is to develop a model in which there is an incentive to adopt a new technology because it increases productivity, but the new technology may require a large adjustment in the level of human capital. The model will be used to explain volatility of growth, growth-rate disasters, counter cyclical human capital accumulations and other empirical observations about economic growth.Real Business Cycle research is a large and very useful literature on the relationship between business cycles, economic growth and technology shocks. But almost all this research assumes that the technology shocks are exogenous and studies how the economy responds to them. This project develops a model in which technology is chosen, total factor productivity depends on current technology and human capital, and human capital can be upgraded at a cost to better match future technology. In this model technology adoption is risky. The risk is one of possibly having the wrong skills and therefore of bearing large costs of retooling and there are additional risks. So choosing a better technology increases tomorrow's productivity directly, but increases the risk that resources will have to be spent to upgrade human capital to keep pace. If growth imposes risks, then it seems like we should observe a positive relation between the growth rate and its volatility. Yet the data show a negative relation between the two over time. This project develops a model that explains this, in that higher volatility leads to a greater mismatch between future technologies and skills and greater retooling costs. The model can be decentralized and extended so that it fits the distribution of growth rates of output, consumption, investment, stock prices, and interest rates observed in post-war U.S. data and elsewhere. Business cycles are partly an outcome of technology choices. This project studies how policy implications hinge on external effects in the use of technology and in the adjustment of human capital.