Sampat BN, Mowery DC, Ziedonis AA "Changes in university patent quality after the Bayh-Dole act:: a re-examination" International Journal of Industrial Organization 21(9):1371-1390 November 2003.

Eugene Garfield garfield at CODEX.CIS.UPENN.EDU
Wed May 26 14:07:50 EDT 2004

B.N.Sampat : bhaven.sampat at

TITLE     Changes in university patent quality after the Bayh-Dole act:
          a re-examination
AUTHOR    Sampat BN, Mowery DC, Ziedonis AA
          1371-1390 NOV 2003

Document type: Article     Language: English     Cited References: 27
Times Cited: 0      Explanation

The Bayh-Dole Act of 1980 facilitated the retention by universities of
patent rights resulting from government funded academic research, thus
encouraging university entry into patenting and licensing. Though the Act
is widely recognized to be a major change in federal policy towards
academic research, surprisingly little empirical analysis has been directed
at assessing its impacts on the academy and on university-industry research
relationships. An important exception is the work of Henderson et al. [Rev.
Econ. Stat. 80 (1998) 119-127] which examined the impact of Bayh-Dole on
the quality of university patents, as measured by the number of times they
are cited in subsequent patents. The authors found that the quality of
academic patents declined dramatically after Bayh-Dole, a finding that has
potentially important policy implications. In this paper, we revisit this
influential finding. By using a longer stream of patent citations data, we
show that the results of the Henderson et al. study reflect changes in the
intertemporal distribution of citations to university patents, rather than
a significant change in the total number of citations these patents
eventually receive. This has important implications not only for the
evaluation of Bayh-Dole, but also for future research using patent
citations as economic indicators. (C) 2003 Elsevier B.V. All rights

Author Keywords:
Bayh-Dole, university patenting, patent citations

KeyWords Plus:

Sampat BN, Georgia Inst Technol, Sch Publ Policy, 685 Cherry St, Atlanta,
GA 30332 USA
Georgia Inst Technol, Sch Publ Policy, Atlanta, GA 30332 USA
Univ Calif Berkeley, Haas Sch Business, Berkeley, CA 94720 USA
Univ Michigan, Sch Business, Ann Arbor, MI 48109 USA
NBER, Cambridge, MA 02138 USA


IDS Number:


Patent Citations and the Post-Bayh-Dole "quality decline"


Patent-based measures have been utilized to measure innovative output for
several decades (Griliches, 1990).  The large variance in the economic and
technological significance of individual patents, however, means that
simple patent counts are noisy indicators of innovative output.  But
weighting patents by the number of times they are cited in subsequent
patents yields a better measure of the technological importance of these
patents (see Trajtenberg, 1990 for one of the first applications of this
measure).  Citations to one patent by many subsequent patents suggests
either that numerous inventions draw on the knowledge embodied in that
patent, and / or that this antecedent patent has opened up a significant
new field of inventive activity, within which follow-on patents must
carefully differentiate their contribution from the prior art represented
by this patent and others.  Scholars have also used citation-weighted
patent counts as measures of the private value of an invention to the
patentholder (Hall et al., 2000; Shane and Klock, 1997;Austin, 1994;
Harhoff et al., 1999, Sampat and Ziedonis, 2003), and still other empirical
work has shown that more heavily cited patents are more likely to be the
subject of litigation, another measure of their economic value (Lanjouw and
Schankerman, 2001).

Our analysis of citations to university patents before and after the Bayh-
Dole Act suggests that there is no decline in the "quality" of university
patents during the 1980s.  The quality decline observed by HJT reflects
truncation of the citations data as well as some change in the
intertemporal distribution of citations to university patents.  These
findings are consistent with earlier results (Mowery and Ziedonis, 2000;
Mowery et al., 2002) that also used longer citation-data time series than
were available to HJT(17).  The sensitivity of these results to truncation
and the difficulties in controlling for truncation in the face of shifts in
citation lags also highlight the sensitivity of patent-citations analyses
to the construction of the relevant datasets.

 Cited Author            Cited Work               Volume      Page Year

 *ASS U TECHN MAN      AUTM LIC SURV FISC Y                            1998
 *ORG EC COORD DEV     BENCHM IND SCI REL                              2002
 *US C JOINT EC COM    ENTR DYN SUCC US HIG                            1999
 *US GEN ACC OFF       GAORCED98126                                    1998
 AUSTIN DH             PATENT CITATIONS APP                            1994
 DASGUPTA P            RES POLICY                    23       487      1994
 EISENBERG R           PUBLIC VERSUS PROPRI                            2001
 EISENBERG R           STI REV                       16        13      1996
 FORAY D               UNESCO WORLD C SCI                              1999
 GRILICHES Z           J ECON LIT                    28      1661      1990
 HALL BH               W7741 NBER                                      2000
 HARHOFF D             REV ECON STAT                 81       511      1999
 HELLER MA             SCIENCE                      280       698      1998
 HENDERSON R           CREATION TRANSFER KN                            1998
 HENDERSON R           NUMBERS UP QUALITY D                            1995
 HENDERSON R           REV ECON STAT                 80       119      1998
 JAFFE AB              J IND ECON                    46       183      1998
 LANJOUW JO            7345 NBER                                       1999
 LANJOUW JO            RAND J ECON                   32       129      2001
 LINK A                ECONOMETRIC ANAL RES                            2002
 MOWERY DC             MANAGE SCI                    48        73      2002
 MOWERY DC             RES POLICY                    31       399      2000
 SAMPAT BN             AAAS CSPO RES S NEXT                            2002
 SAMPAT BN             C EMP EC INN PAT CTR                            2003
 SHANE H               REV QUANTITATIVE FIN           9       131      1997
 TRAJTENBERG M         EC INNOVATION NEW TE           5        19      1997
 TRAJTENBERG M         RAND J ECON                   21       172      1990

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