On the Cyclicality of R&D
研究了研发投入在经济周期中的表现，发现研发是顺周期的，且对需求冲击的反应不对称，流动性约束是重要原因。
We explore the link between short-run cycles and long-run growth by examining the cyclicality of R&D. Existing theories propose that R&D is concentrated when output is low, but aggregate data repeatedly show that R&D appears procyclical. We estimate the relationship between R&D and output using an annual panel of twenty U.S. manufacturing industries from 1958 to 1998. The results indicate that R&D is in fact procyclical, but, interestingly, estimates using demand-shift instruments suggest that it responds asymmetrically to demand shocks. We propose that liquidity constraint is an important cause for the observed procyclicality of R&D. © 2011 The President and Fellows of Harvard College and the Massachusetts Institute of Technology.