The long way around

Zaghouan → Prague → Seattle → Prague

I was born in Zaghouan, a small town in northern Tunisia, nestled beneath the ruins of a Roman aqueduct that once carried water to Carthage. I was three years old when my family moved to Prague.

Nail Hassairi as a child in Zaghouan, Tunisia
Zaghouan, Tunisia. Early 1990s.

It was the mid-1990s. The Czech Republic was still finding its shape after the Velvet Revolution. I grew up speaking Czech in the streets and Arabic at home, navigating two worlds that rarely overlapped. Prague became the place where I learned how to learn—at Gymnázium Jiřího Gutha-Jarkovského, and then at the Institute of Economic Studies at Charles University, where I first encountered the power of data to explain the world.

Czech Summer Camp
Working as an assistant counselor at a Czech children's summer camp
Summer camp in the Czech Republic. Sixteen years old, learning the ropes.
Leading a group of children through the forest at a Czech summer camp, two years later
Two years later. Doksy, Central Bohemia. Leading the group through the woods.

Between semesters I volunteered. I worked as an assistant counselor at children’s summer camps—the classic Czech tábor, wooden cabins in the woods, kids running through sand in the July heat. You learn things about children in those settings that you cannot learn from datasets: how a ten-year-old processes unfairness, what happens when a shy kid is handed responsibility, the precise moment a group tips from play into chaos. These were not research questions yet. But they became the intuition behind the research questions I would ask later.

Grottaglie, Italy · 2009
Volunteering with youth at a nature therapy facility in Grottaglie, Italy, 2009
Volunteering at a psychotherapeutic facility in Grottaglie, Puglia. Disabled youth were treated through nature therapy and socialization with healthy volunteers. Summer 2009.

In the summer of 2009, I went to Grottaglie in Puglia, southern Italy, to work at a psychotherapeutic facility set in the countryside. The program used nature therapy and socialization to support disabled youth—the idea being that structured contact with healthy volunteers, outdoors, in sunlight, could do what clinical settings alone could not. I didn’t have the vocabulary for it then, but this was my first encounter with the question that would define my career: how do environments shape development?

Moravia · 2009
Volunteering with ADRA Czech Republic after devastating floods in Moravia, 2009
With ADRA Czech Republic, cleaning up after the devastating Moravian floods. 2009.

That same year, floods hit Moravia. I joined a volunteer crew with ADRA Czech Republic and spent days shoveling mud out of ruined homes. It was unglamorous, exhausting work—rubber boots, filthy clothes, the smell of river silt in everything. But there was something clarifying about it: when a disaster strips a community to its essentials, you see what the systems were supposed to do and where they failed. Infrastructure, preparedness, response—these are policy questions. I was beginning to see them everywhere.

In 2009, I went to the University of Washington on an exchange program. I was supposed to stay for a year. I stayed for fifteen.

Seattle became the place where everything accelerated. I started a PhD in Economics. I worked at Amazon, which was then becoming the most data-driven organization on the planet—building experimentation infrastructure, learning what it means to make decisions at scale when millions of dollars ride on getting the causal estimate right. I published research on early childhood education, school finance, and the policies that determine which children get access to quality care and which do not.

In 2020 I moved to California, still working for my Seattle employer. In 2024, I came back to Prague—Holešovice, the neighborhood on the bend of the Vltava. The work continues.

Snowboarding above the clouds in the Austrian Alps
Austrian Alps. 2008.

Outside of research, I snowboard, play tennis, cook, and play Go—the ancient board game that has taught me more about strategic thinking than any economics textbook. I believe the best work comes from people who take their craft seriously and their hobbies just as seriously. More about that →