NATIONAL BUREAU OF ECONOMIC RESEARCH
NATIONAL BUREAU OF ECONOMIC RESEARCH
loading...

Patent Citations and the Size of the Inventive Step - Evidence from Hybrid Corn

Petra Moser, Joerg Ohmstedt, Paul W. Rhode

NBER Working Paper No. 21443
Issued in July 2015
NBER Program(s):Development of the American Economy, Productivity, Innovation, and Entrepreneurship

Patents are the main source of data on innovation, but there are persistent concerns that patents may be a noisy and biased measure. An important challenge arises from unobservable variation in the size of the inventive step that is covered by a patent. The count of later patents that cite a patent as relevant prior art – so called forward citations – have become the standard measure to control for such variation. Citations may, however, also be a noisy and biased measure for the size of the inventive step. To address this issue, this paper examines field trial data for patented improvements in hybrid corn. Field trials report objective measures for improvements in hybrid corn, which we use to quantify the size of the inventive step. These data show a robust correlation between citations and improvements in yields, as the bottom line measure for improvements in hybrid corn. This correlation is robust to alternative measures for improvements in hybrid corn, and a broad range of other tests.We also investigate the process, by which patents generate citations. This analysis reveals that hybrids that serve as an input for genetically-related follow-on inventions are more likely to receive self-citations (by the same firm), which suggests that self-citations are a good predictor for follow-on invention.

download in pdf format
   (986 K)

email paper

Machine-readable bibliographic record - MARC, RIS, BibTeX

Document Object Identifier (DOI): 10.3386/w21443

Published: Patent Citations—An Analysis of Quality Differences and Citing Practices in Hybrid Corn Petra Moser, Joerg Ohmstedt, and Paul W. Rhode Management Science 201864:4 , 1926-1940

Users who downloaded this paper also downloaded* these:
Baten, Bianchi, and Moser w21442 Does Compulsory Licensing Discourage Invention? Evidence From German Patents After WWI
Hall, Jaffe, and Trajtenberg w8498 The NBER Patent Citation Data File: Lessons, Insights and Methodological Tools
Atkin and Donaldson w21439 Who's Getting Globalized? The Size and Implications of Intra-national Trade Costs
Abrams, Akcigit, and Grennan w19647 Patent Value and Citations: Creative Destruction or Strategic Disruption?
Lau and Rosen w21432 Are Universities Becoming More Unequal?
 
Publications
Activities
Meetings
NBER Videos
Themes
Data
People
About

National Bureau of Economic Research, 1050 Massachusetts Ave., Cambridge, MA 02138; 617-868-3900; email: info@nber.org

Contact Us