شوک های تکنولوژی، استفاده از سرمایه و قیمت های چسبنده

We quantitatively evaluate a business-cycle environment featuring endogenous capital utilization and nominal price rigidity that illustrates a negative relationship between labor hours and technology (TFP) shocks and a positive relationship between hours and investment (MEI) shocks. Sticky prices induce firms to suppress changes in output due to TFP shocks through changes in the utilization rate of the existing capital stock and labor demand. MEI shocks have an indirect impact on output via their link with capital utilization, and are shown to be the dominant driver of post-1979 US business cycles.

What are the sources of observed fluctuations in macroeconomic aggregates? Following Kydland and Prescott (1982) and Long and Plosser (1983), business-cycle fluctuations are initiated by shocks to total factor productivity (TFP) which proportionately influence the efficiency of productive inputs. While these shocks can be interpreted broadly, they stand in contrast to Keynes’ view that shocks to the marginal efficiency of investment (MEI) are a primary source of business cycles. Greenwood et al. (1988) analyze MEI shocks and match observed fluctuations in output almost as well as Prescott (1986) who only considers shocks to TFP.1

The business-cycle literature offers a vast amount of modelling frictions and mechanisms which have value when considering empirical observations in need of explanation. Our analysis focuses on the exogenous technological sources of business cycles, and addresses some recent empirical analyses suggesting a positive relationship between labor hours and MEI shocks, a negative relationship between labor hours and neutral TFP shocks, and even a negative relationship between output and TFP. We show that an estimated model featuring endogenous capital utilization, nominal price rigidity, real capital rigidity, and endogenous monetary policy has the ability to capture these empirical observations. As eluded to by Basu et al. (2006) and others, sticky nominal prices would be a key feature needed to illustrate the negative relationship between TFP and real variables like labor hours and output because an exogenous increase in supply forces the firms to incur the cost of lowering prices. We show that endogenous capital utilization provides an intensive margin allowing firms to alter the productivity of the pre-existing capital stock. Therefore, a decrease in capital utilization together with a decrease in labor can offset and even decrease the response of output in response to a positive innovation to neutral TFP. Our model predicts a different response to MEI shocks, because they have an indirect impact on output via their link with capital utilization. Furthermore, our analysis suggests that MEI shocks are shown to be the dominant driver of post-1979 US business cycles, but this result is robust to whether we assume rigid or flexible nominal prices.