External Capital Factors and Increasing Returns in U.S. Manufacturing
利用动态成本函数估计，将报酬概念拓展至私人资本的短期准固定性、长期内部规模经济以及外部知识因素（研发、高技术资本、人力资本），基于行业数据发现成本节约带来的规模报酬递增，且知识因素解释了大部分测度到的规模经济。
Theoretical models of endogenous growth identify capital accumulation and returns as a potential stimulus to economic growth. Existing empirical studies, however, are based on a limited notion of these returns, which follows from the simple production function framework used for estimation. The purpose of this study is to examine growth issues using dynamic cost function estimation. This methodology enables us to broaden the concept of returns to include returns arising from short-run quasi-fixity of private capital, long-run (internal) scale economies, and external "knowledge" factors-overall investment in research (R&D), technology (high-tech capital), and education (human capital). Based on detailed industry-level data, we find evidence of increasing returns to scale arising from cost savings on variable inputs, although diminishing returns to capital are prevalent. Our results also show that knowledge factors augment growth. More importantly, they appear to explain a substantial proportion of measured scale economies. "The notion of externalities as a source of increasing returns and productivity growth has a long history in economics, " that has experienced a "recent reawakening of interest." Griliches (1991) © 1997 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology