"Stacking" and "picking" inventions: The patenting behavior of European inventors

By using a sample of 793 inventors drawn from the PatVal-EU dataset, this paper explores three aspects of patent production at the individual inventor level: (1) the number of EPO patents that the inventors produce; (2) the average value of their inventions; (3) the production of the most valuable patents. By jointly estimating the three equations we find that the inventors' level of education, employment in a large firm, and involvement in large-scale research projects positively correlate with quantity. Yet, apart from the size of the research project, none of these factors directly influence the expected value of the inventions. They do, however, have an indirect influence, as we find that the number of patents explains the probability of producing a technological hit (the maximum value). Also, there is no regression to the mean in the invention process at an individual level, as the number of inventions that an inventor produces is not correlated with the average value. © 2007 Elsevier B.V. All rights reserved.