Forthcoming in Research Policy
Citations, Family Size, Opposition and
the Value of Patent Rights
Dietmar Harhoff 1,3, Frederic M. Scherer 2, Katrin Vopel 3
1 Ludwig-Maximilians-Universität Munich (LMU) and CEPR, London
2 John F. Kennedy School, Harvard University
3 Zentrum für Europäische Wirtschaftsforschung (ZEW), Mannheim
July 2002 - Revised Version
Abstract
We combine estimates of the value of patent rights from a survey of
patent holders with a set of indicator variables in order to model the
value of patents. Our results suggest that the number of references to the
patent literature as well as the citations a patent receives are positively
related to its value. References to the non-patent literature are
informative about the value of pharmaceutical and chemical patents, but
not in other technical fields. Patents which are upheld in opposition and
annulment procedures and patents representing large international patent
families are particularly valuable.
Corresponding author: Dietmar Harhoff, Phone: +49-89-2180.2239, fax:+49-89-2180.6284, Email:
harhoff@bwl.uni-muenchen.de - University of Munich – Munich School of Management, Institute for
Innovation Research and Technology Management, D-80539 Munich/Germany – Kaulbachstr. 45
Acknowledgements
Financial support for this study came from the Zentrum für Europäische Wirtschaftsforschung (ZEW) and
the National Science Foundation (NSF). Comments from seminar participants at NBER, the University of
Munich, the University of California at Berkeley and Hebrew University are gratefully acknowledged. We
have profited from comments and suggestions by Zvi Griliches, Adam Jaffe, Jenny Lanjouw, Ariel Pakes,
Suzanne Scotchmer and Ulrich Schmoch. We also thank Johannes Zitzenzier and Horst Hermann Zitt at the
German Patent Office (DPA) who provided us with the data on full-term patents. Birgit Knauer, Rainer
Stuike-Prill and Friedemann Böhm at the Fachinformationszentrum (FIZ) supported us in obtaining the