Analysis of technological innovation based on citation information

The paper discusses the dynamic properties of the patent network. Technological innovation occurs frequently, and predicting where it will happen is difficult because an economic system can adapt to changing technology. We construct a patent network based on the cited relations between patents and analyze the properties of the patent network from January 1976 to December 2005 by using USPTO patent data. We find that technology trends, which are calculated by our measures, are similar with historical trends of technology, showing that our measures would be useful to predict future technology relations. Also, we find that the change of similarity between patents shows meaningful results in terms of technological innovation.