The Meaning of Patent Citations: Report on the NBER/Case-Western Reserve Survey of Patentees

Abstract

Helpful comments from Sam Kortum (including the suggestion to describe the "control" patent in the survey as a "placebo") are gratefully acknowledged. Financial support was provided by the Alfred P. Sloan Foundation, via the Project on Industrial Technology and Productivity at the NBER. The views expressed, and responsibility for all errors, lie with the authors.

Local R&D Strategies and Multilocation Firms: The Role of Internal Linkages

“…A common critique of citation-based measurements is the unknown nature and extent of citations imposed by patent examiners (Jaffe et al 2000). Recent research reveals that examiner citations account for 66% of all citations in an average patent, which may bias empirical tests (Alcacer and Gittelman 2006;Sampat 2009).…”

Mobility of knowledge and local innovation activity

“…A crucial factor is that citations in patents are the results of a highly mediated process, which involves the patent inventor, the patent attorney and the patent examiner. Despite the limitations, studies (Jaffe et al, 2000) have shown that patent citations can be used as a proxy of knowledge flows as about 40% of the inventors surveyed indicated that they learned about the cited invention either before or during the development of their invention. 3 In addition to increasing the rate of innovation -the inventor can just sell the patent to a specialized producer and focus his own efforts on the next invention -patent transactions improve the allocation of technology in an economy.…”

A class of spatial econometric methods in the empirical analysis of clusters of firms in the space

“…These empirical findings are not surprising considering the well-known industrial gap existing between Italian regions and, specifically the dualism between the north and the south of the country. Also, the recent literature on knowledge spillovers and specifically the research that concentrated on patent citation (Jaffe et al, 1993;Breschi and Lissoni, 2001;2006;Driffield, 2006) provides persuasive explanation for the observed geographical pattern. The same kind of information is contained in the graphs reported in Figure 3 In particular Figure 3b shows that the higher concentration observed in the north cannot be due to population concentration and reveals a genuine prevalence of inventors in that area.…”

“…After the recent reinterpretation of Marshall's (Marshall, 1890) insights on 19th-century industrial clustering in space due mainly to Krugman (1991) and Fujita et al (1999), the empirical analysis on this subject has developed along two distinct lines of research. Along the first of these two lines in the literature we record attempts to examine directly the underlying economic mechanism, using the spatial dimension primarily as a source of data.…”

“…In fact a large part of the empirical literature concentrated on measuring the impact of technological spillovers on the innovation performances of regions. In many instances the number of patents and the patents citations have been used as a proxy of the flow of knowledge and of the related innovative output (Jaffe and Trajtenbergerg, 1996;2002;Jaffe et al, 2000). One possible approach is based on the notion of knowledge production function introduced by Griliches (1979) which links regional innovative output with measures of regional innovative inputs like R&D expenses (see e. g. Jaffe 1989; Audretsch e Feldman 1996;Acs et al 1994).…”