Please use this identifier to cite or link to this item: http://hdl.handle.net/10419/93869
Authors: 
von Graevenitz, Georg
Wagner, Stefan
Harhoff, Dietmar
Year of Publication: 
2011
Series/Report no.: 
SFB/TR 15 Discussion Paper 356
Abstract: 
We investigate incidence and evolution of patent thickets. Our empirical analysis is based on a theoretical model of patenting in complex and discrete technologies. The model captures how competition for patent portfolios and complementarity of patents affect patenting incentives. We show that lower technological opportunities increase patenting incentives in complex technologies while they decrease incentives in discrete technologies. Also, more competitors increase patenting incentives in complex technologies and reduce them in discrete technologies. To test these predictions a new measure of the density of patent thickets is introduced. European patent citations are used to construct measures of fragmentation and technological opportunity. Our empirical analysis is based on a panel capturing patenting behavior of 2074 firms in 30 technology areas over 15 years. GMM estimation results confirm the predictions of our theoretical model. The results show that patent thickets exist in 9 out of 30 technology areas. We find that decreased technological opportunities are a surprisingly strong driver of patent thicket growth.
Subjects: 
Patenting
Patent thickets
Patent portfolio races
Complexity
Technological Opportunities
JEL: 
L13
L20
O34
Persistent Identifier of the first edition: 
Document Type: 
Working Paper

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