Identifying Technology Spillovers and Product Market Rivalry
区分了技术溢出（正效应）和产品市场竞争导致的业务窃取（负效应），利用美国企业面板数据发现两种溢出同时存在，但社会净回报远高于私人回报，并评估了三种研发补贴政策。
Support for many R&D and technology policies relies on empirical evidence that R&D \\"spills over\\" between firms. But there are two countervailing R&D spillovers: positive effects from technology spillovers and negative effects from business stealing by product market rivals. We develop a general framework showing that technology and product market spillovers have testable implications for a range of performance indicators, and exploit these using distinct measures of a firm?s position in technology space and product market space. We show using panel data on U.S. firms between 1981 and 2001 that both technology and product market spillovers operate, but that net social returns are several times larger than private returns. The spillover effects are also revealed when we analyze three high-tech sectors in detail - pharmaceuticals, computer hardware and telecommunication equipment. Using the model we evaluate three R&D subsidy policies and show that the typical focus of support for small and medium firms may be misplaced.