On the Cyclicality of Research and Development
指出研发活动具有顺周期性，原因在于研发中存在动态外部性，使企业家短视、在繁荣期集中创新，即使衰退期更优。均衡研发可能过度顺周期，导致宏观冲击对产出有过度持久的影响，增长成本更高。
Economists have recently argued recessions play a useful role in fostering growth. Yet a major source of growth, R&D, is procyclical. This paper argues one reason for procyclical R&D is a dynamic externality inherent in R&D that makes entrepreneurs short-sighted and concentrate their innovation in booms, even when it is optimal to concentrate it in recessions. Additional forces may imply that procyclical R&D is desirable, but equilibrium R&D is likely to be too procyclical, and macroeconomic shocks are likely to have overly persistent effects on output and make growth more costly than in the absence of such shocks.