TY  - JOUR
AU  - Jaffe,Adam B.
AU  - Trajtenberg,Manuel
TI  - Flows of Knowledge from Universities and Federal Labs: Modeling the Flowof Patent Citations Over Time and Across Institutional and Geographic Boundari
JF  - National Bureau of Economic Research Working Paper Series
VL  - No. 5712
PY  - 1996
Y2  - August 1996
UR  - http://www.nber.org/papers/w5712
L1  - http://www.nber.org/papers/w5712.pdf
N1  - Author contact info:
Adam B. Jaffe
PO Box 24390
Wellington 6142
New Zealand
Tel: 64-4-939-4250
E-Mail: adam.jaffe@motu.org.nz

Manuel Trajtenberg
Eitan Berglas School of Economics
Tel-Aviv University
Tel-Aviv 69978
ISRAEL
Tel: 972-3-640-9911
Fax: 972-3-640-9908
E-Mail: manuel@post.tau.ac.il
AB  - The extent to which new technological knowledge flows across institutional and national boundaries is a question of great importance for public policy and the modeling of economic growth. This paper develops a model of the process generating subsequent citations to patents as a lens for viewing knowledge diffusion. We find that the probability of patent citation over time after a patent is granted fits well to a double-exponential function that can be interpreted as the mixture of diffusion and obsolescence functions.  The results indicate that diffusion is geographically localized.  Controlling for other factors, within-country citations are more numerous and come more quickly than those that cross country boundaries.
ER  -