Patent Classification as Indicators of Cognitive Structures

Loet Leydesdorff loet at LEYDESDORFF.NET
Fri Mar 23 06:57:45 EDT 2007

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

.       pdf-version of the full
<> paper

.       html-version of the
<> full paper


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"):


World <>  (135,536 patents;



Andorra <>  (4 patents)
United Arab  <> Emirates (15
Antigua and Barbuda <>  (4 patents)
...., etc.

Spain <>  (1114 patents)
Finland <>  (1651 patents)
France <>  (6958 patents; zipped)
...., etc.

Netherlands <>  (3287 patents)
Norway <>  (665 patents)
New  <> Zealand (444 patents)

....., etc.

Loet Leydesdorff 
Amsterdam School of Communications Research (ASCoR)
Kloveniersburgwal 48, 1012 CX Amsterdam
Tel.: +31-20- 525 6598; fax: +31-20- 525 3681 
 <mailto:loet at> loet at ;

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