A patent only protects an innovator from others producing the same product, but it does not protect him from others producing better products under new patents. Therefore, one may divide up the source of competition facing an innovator into within-patent competition, which results from...

This essay is the introduction to a book of the same title, forthcoming in summer of 2021 from Oxford University Press. The purpose is to document the ways in which patent systems are products of battles over the economic surplus from innovation. The features of these systems take shape as...

Using newly validated data on geographic migration networks, we study how labor demand shocks in the United States propagate across the border with Mexico. We show that the large exogenous decline in US employment brought about by the Great Recession affected demographic and economic outcomes in...

We document the transmission of social distancing practices from the United States to Mexico along migrant networks during the early 2020 Covid-19 pandemic. Using data on pre-existing migrant connections between Mexican and U.S. locations and mobile-phone tracking data revealing social...

In this paper, we propose a new approach to the estimation of social networks and we apply it to the estimation of productivity spillovers in the U.S. Congress. Social networks such as the social connections among lawmakers are not generally directly observed, they can be recovered only using...

We study the relationship between Hispanic employment and location-specific measures of the distribution of jobs. We find that it is only the local density of jobs held by Hispanics that matters for Hispanic employment, that measures of local job density defined for Hispanic poor English...

Sociologists have shown that "third places" such as neighborhood cafés help people maintain and use their network ties. Do they help local entrepreneurs, for whom networks are important? We examine whether the introduction of Starbucks cafés into U.S. neighborhoods with no coffee shops...

This paper shows that the ancestry composition shaped by century-long immigration to the US can explain the current structure of global supply chain networks. Using an instrumental variable strategy, combined with a novel dataset that links firm-to-firm global supply chain information with a US...

We examine friendships and study partnerships among university students over several years. At the aggregate level, connections increase over time, but homophily on gender and ethnicity is relatively constant across time, university residences, and different network layers. At the individual...

The role of friends in the US opioid epidemic is examined. Using data from the National Longitudinal Survey of Adolescent Health (Add Health), adults aged 25-34 and their high school best friends are focused on. An instrumental variable technique is employed to estimate peer effects in opioid...