Linking technical change to research effort: an examination of aggregation and spillovers effects
通过分析印度小麦育种研究的20个项目和50个试验站，发现技术溢出和搭便车现象普遍，尽管总体回报率为55%，但八个项目为负回报，且两个最强项目产生了75%的收益却仅占22%的资源。
We used a disaggregate approach to examine investment efficiency of wheat breeding research in India. India's total research effort comprizes 20 research programs spread across 50 experiment stations. A technology spillover matrix was constructed for both potential and actual spillovers. Spillovers and free-riding were dominant characteristics of technical change during the period studied. Although the aggregate rate of return to wheat improvement research in India was estimated to be 55%, eight programs were found to have earned a negative rate of return when spillins were taken into account. Research output is concentrated on a few strong programs. The two strongest programs generated 75% of all the technical change benefits, even though they claimed just 22% of research resources. These two programs include a significant degree of overlap, while on the other hand many farmers were not reached by any of the programs – 56 and 78% of rainfed and durum area, respectively, in 1990 was still sown with pre-1976 varieties.