Productivity in innovation. The role of inventor connections and mobility

This article studies the contribution of different channels of knowledge transfer on innovation output, measured by patent production. The study verifies whether there exists a productivity increase in innovation activity induced by inventor-firm networks and inventors’ mobility. On the one hand, we measure the size of interfirm-networks that originate through researchers’ employment relationships; in other words, we observe each firm’s ties (to other firms) originated by the contribution of its researchers to other firms’ patents (variable Networks). Secondly, we study the transfer of knowledge occurring through the mobility of researchers/innovators (variable Mobility). We use two different measures of Networks. A first proxy of Networks of any applicant i at time t is made by summing up the number of inventors (“shared” inventors) listed in correspondence of any patent application of this applicant at time t, and participating, at the same t, in patent applications of other applicants. A second measure of Networks is given by the number of applicants to which applicant i is “connected” to, at time t, by means of each “shared” inventor. Mobility is defined as the number of inventors having applied for a patent, at time t, with any applicant, but not having shared in the past any other patent application with the same applicant; on the contrary, they need to have contributed to other applicants’ patents. In other words, an inventor, who has been already listed in the dataset in correspondence to a patent filed some years before, is considered mobile if he collaborates, in a given year, to a patent filed by an applicant with whom he did not cooperate in the past. Resuming the debate on the localization of knowledge transfer and the existence of productivity lags, the paper focuses on the role played by geographical proximity, and on the dynamic effects of knowledge flows. The geographical issue is faced at a very detailed level; we measure knowledge flows observed within the same Local Labor System (Intra-LLS), between different LLSs of the region (Inter-LLSs) and from LLSs outside the region (Extra-region).