Patent Classifications as Indicators of Cognitive Structures
Paper to be presented at the Annual Meeting of the
Society for the Social Studies of Science (4S),
Montreal, October 2007
Loet Leydesdorff
Amsterdam School of Communications Research (ASCoR), University of Amsterdam
Kloveniersburgwal 48, 1012 CX Amsterdam, The Netherlands
loet@leydesdorff.net ; http://www.leydesdorff.net
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Using the 138,751 patents filed in 2006 under the Patent Cooperation Treaty, co-classification analysis is pursued on the basis of three- and four-digit codes in the International Patent Classification (IPC, 8th edition). The initial hypothesis that classifications might be considered as the organizers of patents into classes, and that therefore co-classification patterns would be useful for mapping, is discarded in favor of using co-word analysis among titles of patents. The classifications hang weakly together, even at the four-digit level; at the country level, more specificity can be made visible. The co-classifications among the patents enable us to analyze and visualize the relations among technologies at different levels of aggregation. However, countries are not the appropriate units of analysis because patent portfolios are largely similar in many advanced countries in terms of the classes attributed.
The following files are input files for Pajek based on the cosines between the 4-digit classifications for each country separately and for the complete set ("World"):
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World (135,536 patents; zipped) |
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Andorra
(4 patents) |
Spain
(1114 patents) |
Netherlands
(3287 patents) |