NBER Working Papers by David C. Mowery

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Working Papers

June 2007Pioneers, Submariners, or Thicket-builders: Which Firms Use Continuations in Patenting?
with Deepak Hegde, Stuart Graham: w13153
The continuations procedure within the U.S. patent system has been criticized for enabling firms to manipulate the patent review process for strategic purposes. Changes during the 1990s in patent procedures affected the incentives of applicants to exploit the continuations process, and additional reforms in continuations currently are being considered. Nonetheless, little is known about applicants' use of the three major types of continuations -- the Continuation Application (CAP), the Continuations-In-Part (CIP), and Divisions -- to alter the term and scope of patents. This paper analyzes patents issued from the three types of continuations to U.S. firms during 1981 - 2004 (with priority years 1981 - 2000), and links their frequency to the characteristics of patents, assignees and indu...
February 2002Post-Issue Patent "Quality Control": A Comparative Study of US Patent Re-examinations and European Patent Oppositions
with Stuart J. H. Graham, Bronwyn H. Hall, Dietmar Harhoff: w8807
We report the results of the first comparative study of the determinants and effects of patent oppositions in Europe and of re-examinations on corresponding patents issued in the United States. The analysis is based on a dataset consisting of matched EPO and US patents. Our analysis focuses on two broad technology categories - biotechnology and pharmaceuticals, and semiconductors and computer software. Within these fields, we collect data on all EPO patents for which oppositions were filed at the EPO. We also construct a random sample of EPO patents with no opposition in these technologies. We match these EPO patents with the 'equivalent' US patents covering the same invention in the United States. Using the matched sample of USPTO and EPO patents, we compare the determinants of opposition...
October 2001The Geographic Reach of Market and Non-Market Channels of Technology Transfer: Comparing Citations and Licenses of University Patents
with Arvids A. Ziedonis: w8568
The growth of high-technology clusters in the United States suggests the presence of strong regional agglomeration effects that reflect proximity to universities or other research institutions. Using data on licensed patents from the University of California, Stanford University, and Columbia University, this paper compares the geographic 'reach' of knowledge flows from university inventions through two important channels: non-market 'spillovers' exemplified by patent citations and market contracts (licenses). We find that knowledge flows through market transactions to be more geographically localized than those operating through non-market 'spillovers.' Moreover, the differential effects of distance on licenses and citations are most pronounced for exclusively licensed university paten...
March 1987Firm Size and R&D Intensity: A Re-Examination
with Wesley M. Cohen, Richard C. Levin: w2205
Using data from the Federal Trade Commission's Line of Business Program and survey measures of technological opportunity and appropriability conditions, this paper finds that overall firm size has a very small, statistically in- significant effect on business unit R & D intensity when either fixed industry effects or measured industry characteristics are taken into account. Business unit size has no effect on the R & D intensity of business units that perform R & D, but it affects the probability of conducting R & D. Business unit and firm size jointly explain less than one per cent of the variance in R & D intensity; industry effects explain nearly half the variance.

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