Firms and Aggregate Dynamics
研究永久性和暂时性冲击对企业与总体经济动态的影响，发现永久性冲击主导企业波动但跨企业几乎不相关，而暂时性冲击虽对企业不重要却因高度相关而解释总体波动。
We investigate the role of permanent and transitory shocks for firms and aggregate dynamics. We find that permanent shocks to productivity and permanent shifts in the composition of output explain at least four-fifths of firms' dynamics. However, these permanent shocks are almost uncorrelated across firms and are therefore less relevant for aggregate dynamics. Transitory shocks, on the other hand, are not very important at the firm level, but they account for most of the volatility of aggregate hours and output, because they are significantly correlated across firms. Finally, we try to make some progress on the interpretation of the shocks. Copyright by the President and Fellows of Harvard College and the Massachusetts Institute of Technology.