Monetary Policy Responses to Exogenous Shocks
利用55个发达国家和发展中国家的647个观测数据，检验了货币政策对外生冲击（如1973-74年石油价格冲击）的应对效果。研究发现，货币宽松在短期内能抵消冲击对产出增长的负面影响，但长期会通过增加货币增长冲击的方差而降低产出增长。
The oil-price shocks of 1973-74 and 1979-80 reduced output growth in oil-importing countries. Using monetary policy to accommodate exogenous shocks of this kind undoubtedly works. But the more such monetary policy is used, the less effective it becomes. And discretionary monetary policy has a negative effect on economic growth in the long run. This is how we interpret the econometric results reported below. We find that money is neutral neither in the medium term nor in the long run. The effects of current and lagged money growth shocks on output growth are significantly positive. Over time, however, discretionary monetary policy creates a higher variance of money growth shocks. The period-average variance of money growth shocks together with our indicator of an accommodative monetary policy regime are both negatively related to the rate of growth in real gross domestic product (GDP). Higher variance of money growth shocks reduces both the medium-term impact of discretionary monetary policy on output growth and output growth itself in the long run (see Robert Lucas, 1973, and Roger Kormendi and Philip Meguire, 1984, 1985). The only way of testing both the mediumand long-run effects of discretionary monetary policy is by pooling time-series data across countries; we use 647 observations for 55 developed and developing countries. We believe this to be the first appropriate test. Monetary accommodation of exogenous shocks, specifically accommodation of the 1973-74 oil-price increase, works temporarily to offset the output growth-reducing impact of the shock. However, accommodation adds noise to the economic environment and reduces output growth in the longer run. Indeed, we find that our monetary accommodation variable performs in virtually the same way as the variance of money growth shocks. Expansionary fiscal policy has mediumand long-run effects on output growth that are similar to monetary accommodation. Specifically, expansionary fiscal policy raises the ratio of net government credit to total domestic credit in countries lacking well-developed direct financial markets. In the medium term, a positive government credit shock raises output growth by stimulating aggregate demand. But a higher government credit ratio lowers output growth in the long run by starving the private sector of finance for productive investment.