NATIONAL BUREAU OF ECONOMIC RESEARCH
NATIONAL BUREAU OF ECONOMIC RESEARCH

Joerg Ohmstedt

Department of Economics
Cornell University
Ithaca, NY

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NBER Working Papers and Publications

July 2015Patent Citations and the Size of the Inventive Step - Evidence from Hybrid Corn
with Petra Moser, Paul W. Rhode: w21443
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 a...

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

 
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