Abstract

http://ssrn.com/abstract=1888191
 
 

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Do Patent Citations Measure the Size of the Inventive Step? Evidence from Hybrid Corn


Petra Moser


Stanford University - Department of Economics; National Bureau of Economic Research (NBER)

Joerg Ohmstedt


Booz & Company

Paul W. Rhode


University of North Carolina (UNC) at Chapel Hill - Department of Economics; National Bureau of Economic Research (NBER); University of Arizona

July 30, 2014


Abstract:     
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.

Number of Pages in PDF File: 48

Keywords: innovation, patents, intellectual property, hybrid corn

JEL Classification: O30, O31, O33, O34, L70, Q10

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Date posted: July 18, 2011 ; Last revised: July 31, 2014

Suggested Citation

Moser, Petra and Ohmstedt, Joerg and Rhode, Paul W., Do Patent Citations Measure the Size of the Inventive Step? Evidence from Hybrid Corn (July 30, 2014). Available at SSRN: http://ssrn.com/abstract=1888191 or http://dx.doi.org/10.2139/ssrn.1888191

Contact Information

Petra Moser (Contact Author)
Stanford University - Department of Economics ( email )
Landau Economics Building
579 Serra Mall
Stanford, CA 94305-6072
United States
National Bureau of Economic Research (NBER)
1050 Massachusetts Avenue
Cambridge, MA 02138
United States
Joerg Ohmstedt
Booz & Company ( email )
101 Park Avenue
New York, NY 10178
United States
Paul Rhode
University of North Carolina (UNC) at Chapel Hill - Department of Economics ( email )
Chapel Hill, NC 27599
United States
National Bureau of Economic Research (NBER)
1050 Massachusetts Avenue
Cambridge, MA 02138
United States
University of Arizona
Tucson, AZ 85721
United States
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