Stars and Comets: An Exploration of the Patent Universe

The analysis of patent and citation data has become a popular source of evidence on localizedknowledge spillovers and innovation. Nevertheless, an aspect has been overlooked: the patentdistribution across inventors is extremely skewed, as many inventors register one or a fewpatents, while a small number of inventors register many patents. To our knowledge, theprevious empirical literature has not discussed the different kinds of local innovation fromwhich patents may originate. A first contribution of this paper is therefore to document theissue. A second contribution is to investigate whether patents originating from differentscales of innovation are located in different cities. A third contribution - which constitutes themain scope of the paper - is to test whether the concentration of the activity of star inventorsis beneficial to the local productivity of other kinds of innovation - namely the ones led bymore occasional, and less prolific, inventors.