A Nonparametric Analysis of the Influence of Research on Agricultural Productivity
用非参数方法分析公共和私人研究支出对美国农业生产力随时间的影响，发现公共研究需30年才能完全见效，长期回报率高于私人研究。
Abstract Nonparametric productivity analysis is extended by modeling technical progress as a function of public and private research expenditures. Results indicate that 30‐year lags are required to fully capture the effects of public research expenditures on U.S. agricultural productivity. Compared to public research, private research has a stronger influence on farm productivity in the short term but a smaller influence in the longer term. The internal rate of return is 0.28 for public research and 0.17 for private research.