The Invariance of Market Innovation to the Number of Firms
给出条件，使得市场经济中的研发投入不随企业数量或规模分布变化，且市场配置是有效的。分析表明，企业选择和创新技术的刻画方式对研发经济分析的结论有重要影响。
This article provides a set of conditions under which the R and D undertaken in a market economy is invariant to the number (or size distribution) of firms and the market's allocation is efficient (i.e., given the aggregate expenditure, the market chooses socially optimal projects). As in several patent race studies, we assume that a "winner-takes-all" competition determines firms' gains, but our model differs from earlier studies in that firms are not restricted to undertake only one research project. Our analysis shows that how one characterizes a firm's choices (and innovation technologies) has a strong influence on the conclusions one draws from economic analyses of R and D.