(NAS Colloquium) Science, Technology and the Economy (1996) / Chapter Skim
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Flows of knowledge from universities and federal laboratories: Modeling the flow of patent citations over time and across…
Flows of knowledge from universities and federal laboratories: Modeling the flow of patent citations over time and across…
Pages 17-23
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From page 17... ...
We and others have discussed elsewhere at great length the advantages and disadvantages of using patents and patent citations to indicate inventions and knowledge links among inventions (3-5~. Patent citations perform the legal function of delimiting the patent right by identifying previous patents whose technological scope is explicitly placed outside the bounds of the citing patent.
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From page 18... ...
USA 93 (1996) United States United States United States corporations universities government Range of cited patents 1963-1990 1965-1990 1963-1990 Range of citing patents 1977-1993 1977-1993 1977-1993 Total potentially cited patents SS,257 10,761 38,954 (1 in 10)
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From page 19... ...
the grant year of the potentially citing patent, and L = 1..5, the location of the potentially citing patent. To illustrate the plausibility of this formulation, we plot the average citation functions (citation frequency as a function of time elapsed from the potentially cited patent)
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From page 20... ...
* O-5, where nisi is the number of potentially cited patents and nTL the number of potentially citing patents corresponding to a given cell.
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From page 21... ...
2, where we plot the predicted citation function for patents in Electronics, Optics, and Nuclear, versus patents in the base field ("All Others. Patents in electronics are much more highly cited during the first few years after grant; however, due to their faster obsolescence, in later years they are actually less cited than those in the base group.
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From page 22... ...
That is, patents granted to United States inventors are much more likely to cite previous United States patents than are patents granted to inventors of other countries: cat for the different foreign regions/countries is in the 0.43-0.57 range, as opposed to the (normalized) value of 1 for the United States.
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From page 23... ...
Citation probability ratio by citing geographic area Location 51 Canada 0.914 Europe 0.899 Japan 1.002 Rest of World 0.900 United States 1 non Lag, yr 1 5 10 0.58 0.62 0.44 0.48 0.44 0.44 0.44 0.48 1.00 1.00 0.67 0.53 0.44 0.33 1.00 20 30 0.80 0.95 0.65 0.79 0.44 0.44 0.64 0.78 1.00 1.00 Interestingly, we do not find that university patents are, to any significant extent, more likely to be cited after long periods of time. Finally, we show that citation patterns across technological fields conform to prior beliefs about the pace of innovation and the significance of "gestation" lags in different areas, with Electronics, Optics, and Nuclear Technolog showing very high early citation but rapid obsolescence, why; ~ as Drugs and Medical Technology generate significant citations for a very long time.
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