Lens or Prism? Patent Citations as a Measure of Knowledge Flows from Public Research

Management Science (2013), 59(2): DOI/10.1287/mnsc.1120.1644

51 Pages Posted: 30 Aug 2011 Last revised: 5 Aug 2017

See all articles by Michael Roach

Michael Roach

University of Illinois at Urbana-Champaign - Gies College of Business

Wesley M. Cohen

Duke University - Fuqua School of Business; Duke University - Department of Economics; National Bureau of Economic Research (NBER); Duke Innovation & Entrepreneurship Initiative

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Date Written: July 2012

Abstract

This paper assesses the validity and accuracy of firms’ backward patent citations as a measure of knowledge flows from public research by employing a newly constructed dataset that matches patents to survey data at the level of the R&D lab. Using survey-based measures of the dimen-sions of knowledge flows, we identify sources of systematic measurement error associated with backward citations to both patent and nonpatent references. We find that patent citations reflect the codified knowledge flows from public research, but they appear to miss knowledge flows that are more private and contract-based in nature, as well as those used in firm basic research. We also find that firms’ patenting and citing strategies affect patent citations, making citations less indicative of knowledge flows. In addition, an illustrative analysis examining the magnitude and direction of measurement error bias suggests that measuring knowledge flows with patent citations can lead to substantial underestimation of the effect of public research on firms’ innova-tive performance. Throughout our analyses we find that nonpatent references (e.g., journals, con-ferences, etc.), not the more commonly used patent references, are a better measure of knowledge originating from public research.

Keywords: patent citations, knowledge flows, universities, innovation, measurement

Suggested Citation

Roach, Michael and Cohen, Wesley M., Lens or Prism? Patent Citations as a Measure of Knowledge Flows from Public Research (July 2012). Management Science (2013), 59(2): DOI/10.1287/mnsc.1120.1644, Available at SSRN: https://ssrn.com/abstract=1911965 or http://dx.doi.org/10.2139/ssrn.1911965

Michael Roach (Contact Author)

University of Illinois at Urbana-Champaign - Gies College of Business ( email )

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Wesley M. Cohen

Duke University - Fuqua School of Business ( email )

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