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We investigate the relationship between patenting activity and the population size of metropolitan areas in the United States over the last two decades (1980–2001). We find a clear superlinear effect, whereby new patents are granted disproportionately in larger urban centers, thus showing increasing returns in inventing activity with respect to population(More)
With urban population increasing dramatically worldwide, cities are playing an increasingly critical role in human societies and the sustainability of the planet. An obstacle to effective policy is the lack of meaningful urban metrics based on a quantitative understanding of cities. Typically, linear per capita indicators are used to characterize and rank(More)
W hereas a number of studies have considered the implications of employee mobility, comparatively little research has considered institutional factors governing the ability of employees to move from one firm to another. This paper explores a legal constraint on mobility—employee non-compete agreements—by exploiting Michigan's apparently inadvertent 1985(More)
This is an Open Access article distributed under the terms of the Creative Commons Attribution-Non-Commercial-Share Alike License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. This license does not permit commercial exploitation or the creation of derivative works(More)
While prior research has considered the desirability and implications of employee mobility, less research has considered factors affecting the ease of mobility. This paper explores a legal constraint on mobility —employee noncompete agreements—by exploiting Michigan's apparently-inadvertent 1985 reversal of its enforcement policy as a natural experiment.(More)
Invention has been commonly conceptualized as a search over a space of combinatorial possibilities. Despite the existence of a rich literature, spanning a variety of disciplines, elaborating on the recombinant nature of invention, we lack a formal and quantitative characterization of the combinatorial process underpinning inventive activity. Here, we use US(More)
  • Li Jin, I Thank, Malcolm Baker, Dan Bergstresser, Long Chen, Josh Coval +29 others
  • 2004
S for providing analyst forecasts data, and SEC for providing data on the investment advisor profiles. I am grateful to the extensive effort by Harvard Business School Special Projects Group, led by Toni Wegner, in cleaning up the data used in this project. I also benefited from talks with David Granger and Melvyn Gonzalez at Thompson Financials to(More)
The factors that account for the differences in the economic productivity of urban areas have remained difficult to measure and identify unambiguously. Here we show that a microscopic derivation of urban scaling relations for economic quantities vs. population, obtained from the consideration of social and infrastructural properties common to all cities,(More)
Urban areas consume more than 66% of the world's energy and generate more than 70% of global greenhouse gas emissions. With the world's population expected to reach 10 billion by 2100, nearly 90% of whom will live in urban areas, a critical question for planetary sustainability is how the size of cities affects energy use and carbon dioxide (CO2) emissions.(More)