Measuring the Social Return to R&D
在增长模型中推导了研发社会回报率与实证文献系数估计的关系，表明这些估计是下限，并指出最优研发投资至少是实际投资的2到4倍。
Is there too much or too little research and development (R&D)? In this paper we bridge the gap between the recent growth literature and the empirical productivity literature. We derive in a growth model the relationship between the social rate of return to R&D and the coefficient estimates of the empirical literature and show that these estimates represent a lower bound. Furthermore, our analytic framework provides a direct mapping from the rate of return to the degree of underinvestment in research. Conservative estimates suggest that optimal R&D investment is at least two to four times actual investment.