R&D and Economic Growth
比较了竞争经济中研发的总体率与最优率，发现最优率在广泛偏好族中相同，而竞争率因产品替代性形式不同而变化，且次优研发率等于最优率。数值例子表明创新技术收益递减是竞争经济中研发过度的最重要潜在来源。
The aggregate rate of R&D in a competitive economy is compared with the optimal rate. The optimal rate of R&D is shown to be the same for all preferences in a broad family, while the competitive rate is sensitive to the form of substitutability among products and so can vary dramatically within a family. The second-best level of R&D is shown to be also common within a family and equal to the optimal rate. Numerical examples suggest that diminishing returns in the innovation technology is the most important potential source for excessive R&D in a competitive economy.