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Applicant and Examiner Citations in US Patents: An Overview and Analysis

Author

Listed:
  • Juan Alcacer

    () (Harvard Business School, Strategy Unit)

  • Michelle Gittelman

    () (Rutgers Business School, Rutgers University)

  • Bhaven Sampat

    () (Malman School of Public Health, Columbia University)

Abstract

Researchers studying innovation increasingly use indicators based on patent citations. However, it is well known that not all citations originate from applicants--patent examiners contribute to citations listed in issued patents--and that this could complicate interpretation of findings in this literature. In 2001 the US Patent and Trademark Office (USPTO) began reporting examiner and applicant citations separately. In this paper, we analyze the prior art citations of all patents granted by the USPTO in 2001-2003. We show that examiner citations account for 63 per cent of all citations on the average patent, and that 40 per cent of patents have all citations added by examiners. We use multivariate regression and analysis of variance to identify the determinants of examiner shares. Examiner shares are highest for non-US applicants and in electronics, communications, and computer-related fields. However, most of the variation is explained by firm-specific variables, with the largest patent applicants having high examiner shares. Moreover, a large number of firms are granted patents that contain no applicant prior art. Taken together, our findings suggest that heterogeneity in firm-level patenting practices, in particular by high-volume applicants, has a strong influence on the data. This suggests that analysis of firm-level differences in patenting strategies is an important topic for future research.

Suggested Citation

  • Juan Alcacer & Michelle Gittelman & Bhaven Sampat, 2008. "Applicant and Examiner Citations in US Patents: An Overview and Analysis," Harvard Business School Working Papers 09-016, Harvard Business School.
  • Handle: RePEc:hbs:wpaper:09-016
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    References listed on IDEAS

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    1. Popp David & Juhl Ted & Johnson Daniel K.N., 2004. "Time In Purgatory: Examining the Grant Lag for U.S. Patent Applications," The B.E. Journal of Economic Analysis & Policy, De Gruyter, vol. 4(1), pages 1-45, November.
    2. Allison, John R. & Lemley, Mark & Moore, Kimberly A. & Trunkey, Derek, 2003. "Valuable Patents," Berkeley Olin Program in Law & Economics, Working Paper Series qt1m16k7w3, Berkeley Olin Program in Law & Economics.
    3. Wesley M. Cohen & Richard R. Nelson & John P. Walsh, 2000. "Protecting Their Intellectual Assets: Appropriability Conditions and Why U.S. Manufacturing Firms Patent (or Not)," NBER Working Papers 7552, National Bureau of Economic Research, Inc.
    4. Ashish Arora & Andrea Fosfuri & Alfonso Gambardella, 2004. "Markets for Technology: The Economics of Innovation and Corporate Strategy," MIT Press Books, The MIT Press, edition 1, volume 1, number 0262511819, January.
    5. Schneider, C├ędric, 2007. "The Determinants of Patent Applications Outcomes - Does Experience Matter?," MPRA Paper 3359, University Library of Munich, Germany.
    6. Papke, Leslie E & Wooldridge, Jeffrey M, 1996. "Econometric Methods for Fractional Response Variables with an Application to 401(K) Plan Participation Rates," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 11(6), pages 619-632, Nov.-Dec..
    7. Manuel Trajtenberg & Adam B. Jaffe & Michael S. Fogarty, 2000. "Knowledge Spillovers and Patent Citations: Evidence from a Survey of Inventors," American Economic Review, American Economic Association, vol. 90(2), pages 215-218, May.
    8. Lerner, Josh, 1995. "Patenting in the Shadow of Competitors," Journal of Law and Economics, University of Chicago Press, vol. 38(2), pages 463-495, October.
    9. Anders Skrondal & Sophia Rabe-Hesketh, 2007. "Latent Variable Modelling: A Survey," Scandinavian Journal of Statistics, Danish Society for Theoretical Statistics;Finnish Statistical Society;Norwegian Statistical Association;Swedish Statistical Association, vol. 34(4), pages 712-745.
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    Cited by:

    1. Griffith, Rachel & Lee, Sokbae & Straathof, Bas, 2017. "Recombinant innovation and the boundaries of the firm," International Journal of Industrial Organization, Elsevier, vol. 50(C), pages 34-56.

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    Keywords

    Technology; patents; patent examiners; prior art; citations;

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