Research Statement
At the core of my research is one of the most fundamental questions in economics
Why are some countries rich while others are poor?
My work shows that the answer hinges on how knowledge moves—and, crucially, on how people move with it.
Scroll to explore my research
We know cross-country income gaps are largely—over 60 percent—explained by productivity differences. Productivity simply put is the ability to generate more value with the same inputs.
In my view productivity is about having the knowledge to do more with the same resources.
But knowledge is non-rival and non-excludable—so why doesn't it flow freely?
Much of what matters is tacit knowledge—like riding a bike or flying a plane, skills that can't be learned from books alone.
This is the knowledge workers carry in factories and managers apply in firms. It drives productivity—and it's embodied in people.
Knowledge does not diffuse frictionlessly. Despite globalization, productive know-how remains geographically concentrated.
We have shown that countries develop comparative advantages similar to their neighborsNeighbors and the Evolution of the Comparative Advantage of NationsRead paper →—knowledge spreads very locally. At the firm level, I showed that multinationals locate knowledge-intensive activities near headquartersThe Hardships of Long Distance Relationships: Time Zone Proximity and MNCsRead paper →, expanding further only when in the same time zone.
People move knowledge in ways markets alone cannot. If knowledge is tacit and hard to transfer, then the most effective way to move it is to move the people who carry it.
This is a central piece of my research agenda: demonstrating how migrants are powerful agents of knowledge diffusion.
Huguenot Memorial, Franschoek. French Huguenot refugees brought winemaking expertise to South Africa in the 17th century. Photo Credit: Dany Bahar Migration transforms comparative advantage. In some of my early workMigration, Knowledge Diffusion and the Comparative Advantage of NationsRead paper →, we showed that immigrants make their destination more likely to export products their home countries specialize in—evidence that migrants carry tacit productive knowledge.
Consistently, in another central paper of my portfolioMigration and Knowledge Diffusion: The Effect of Returning Refugees on Export PerformanceRead paper → we find that industries where Yugoslav refugees worked in Germany showed stronger export performance after their return.
Ismael Mena pioneered medical instruments patents in Chile after patenting in the same technology class in Los Angeles—a Global Mobile Inventor. Photo: ALASBIMN Journal / CC BY-SA 3.0 Mobility also defines global innovation dynamics. In a paper with my longtime coauthors Raj Choudhury and Hillel RapoportMigrant Inventors and the Technological Advantage of NationsRead paper → we show that countries are more likely to develop new technological capabilities when they host immigrant inventors from nations already specialized in those technologies.
Consistently, in a following paper using inventor-level dataGlobal Mobile InventorsRead paper → we document the phenomenon of Global Mobile Inventors—inventors who patent in more than one country over their lifetime. We find these inventors are disproportionately likely to pioneer new technologies.
For migration to drive development, integration must succeed. The gains from migration depend on whether newcomers can fully participate in labor markets.
We studied Colombia's amnesty for VenezuelansGive Me Your Tired and Your Poor: Impact of a Large-Scale Amnesty ProgramRead paper →—finding significant gains for beneficiaries with no harm to natives. Legalization also empowered migrants to report crimesEmpowering Migrants: Impacts of a Migrant's Amnesty on Crime ReportsRead paper → and increased their business formation tenfoldLegalizing EntrepreneurshipRead paper →.
With Rebecca Brough and Giovanni PeriThe Economics of Refugees' Economic IntegrationRead paper →, we synthesized decades of evidence on what works for refugee integration.
The demographic shift of aging societies makes migration policy more urgent than ever. These societies face persistent labor shortages that domestic labor supply alone cannot resolve.
Consistently, I have shownNot a Border Crisis, but a Labor Market CrisisRead paper → that border crossings in the United States rise and fall with labor market tightness—migration responds to economic demand. Especially over the past few years, what we call a "border crisis" is fundamentally a labor market phenomenon. NPR The Indicator
The question is no longer whether countries need migrants, but whether they will design policies that allow migration to work—for migrants and for host societies alike.
Migration will define the wealth of nations. In the 21st century, prosperity will depend less on where ideas are born and more on whether societies allow ideas to move with people.
This argument—and the evidence behind it—forms the core of my forthcoming book.