Private Value of European Patents
The author examines the joint patent designation-renewal behavior of the EPO patent applicants during 1978 to 1996, using both nonparametric technique and a parametric model. Findings indicate that the value of patent rights increases with the economics size of the country and has a modestly increasing returns to scale.
Link
ftp://ftp1.economics.smu.edu/WorkingPapers/2005/Deng/patent_aug2005.pdf