TY  - JOUR
AU  - Hall,Bronwyn H.
AU  - Griliches,Zvi
AU  - Hausman,Jerry A.
TI  - Patents and R&D:  Is There A Lag?
JF  - National Bureau of Economic Research Working Paper Series
VL  - No. 1454
PY  - 1986
Y2  - October 1986
UR  - http://www.nber.org/papers/w1454
L1  - http://www.nber.org/papers/w1454.pdf
N1  - Author contact info:
Bronwyn H. Hall
Dept. of Economics
549 Evans Hall
UC Berkeley
Berkeley, CA 94720-3880
Tel: 510/642-3878
Fax: 510/548-5561
E-Mail: bhhall@nber.org

Zvi Griliches
E-Mail: N/A user is deceased

Jerry A. Hausman
Department of Economics
MIT, Room E52-271A
50 Memorial Drive
Cambridge, MA  02139
Tel: 617/253-3644
Fax: 617/253-1330
E-Mail: jhausman@mit.edu
AB  - This paper extends earlier work on the RID to patents relationship (Pakes-Griliches 1980, and Hausman, Hall, and Griliches,1984) to a larger but shorter panel of firms. The focus of the paper is on solving a number of econometric problems associated with the discreteness of the dependent variable and the shortness of the panel in the time dimension. We compare weighted nonlinear least squares as wellas Poisson-type models as solutions to the former problem. In attempting to estimate a lag structure on R&D in the absence of a sufficient history of the variable, we take two approaches: first, we use the conditional version of the negative binomial model, and second, we estimate the R&D variable itself as a low order stochastic process and use this information to control for unobserved R&D. R&D itself turns out to befairly well approximated by a random walk. Neither approach yields strong evidence of a long lag. The available sample, though numerically large, turns out not to be particularily informative on this question. It does reconfirm, however, a significant effect of R&D on patenting (with most of it occuring in the first year) and the presence of rather wide and semi-permanent differences among firms in their patenting policies.
ER  -