Modelling the Connections in the Cross Section between Technical Progress and R&D Intensity
解释行业间技术进步与研发强度正相关的原因，通过模型分析技术机会和专有性如何影响这两个变量，发现技术机会差异是关键，专有性差异则使关系变得模糊。
This article is concerned with explaining the observed positive relationship in a cross section of industries between technical advance and R&D intensity. It presents a set of models to explore how technological opportunity and appropriability affect both of these variables. The models suggest that the key factors explaining the relationship are differences across industries in technological opportunity. Differences in appropriability make the relationship noisy.