Dissertation Title: Cities, networks, and knowledge spillovers
Economies grow as a result of new ideas enabling innovations that render existing technologies obsolete. Yet, explaining economic growth by using the growth of ideas just pushes the question a step further. If growth comes from new ideas, where do ideas come from? With the availability of new data sources on inputs and outputs of innovation, we have started to build a fairly accurate description of our idea-producing machine. A picture emerges where ideas are cumulative, innovation relies on the ability of ecosystems to produce complex combinations of new ideas, and geography still poses a barrier for knowledge exchange. This work contributes to our understanding of innovation by documenting three stylized facts about knowledge creation: the type of knowledge matters for new companies, complex knowledge is better produced in large cities, and urban vibrancy can help enhance knowledge spillovers. First, we document that when starting new ventures, knowledge about the industry is more important than knowledge about the occupations involved. Second, we find that complex economic activities tend to be disproportionately concentrated in large cities and that this concentration has been growing for the past one hundred and fifty years. Third, we use the staggered rollout of state-level R&D tax credits in the US together with department-level publication data to measure the benefit to university researchers working in close physical proximity to private researchers. We find that urban vibrancy plays a role in increasing the spillovers to academia. Our understanding of innovation used to be based on speculation built on anecdotes and stories of success. With the availability of new data sources and platforms that track different pieces of our idea-making machine, we are no longer restricted to study innovation by focusing only on the big winners.
Kent Larson, Director, City Science Group
César Hidalgo, ANITI Chair, University of Toulouse
Edward Glaeser, Professor of Economics, Harvard University
Scott Stern, Professor of Management, Massachusetts Institute of Technology