Daniel Björkegren uses big data to understand the economics of the developing world. It’s an approach that speaks to the unusual path he took to becoming an economist.

When he started college, Björkegren had already interned at Microsoft and had plans to become a computer scientist. But those plans changed when he took a mission trip to inner-city Los Angeles during his freshman year.

“I was working with homeless people and poor families and it really challenged me,” said the new assistant professor of economics. “I thought, if my life’s work makes computers a little bit faster, what difference does that make in these bigger problems of poverty and people being stuck on the margins of society.”

Following that experience, Björkegren changed his major to physics, thinking his way of making a difference could be to become a science teacher. After graduating, he spent a year teaching science in a Texas high school through the Teach for America program.

But it was a bit later, while earning his master’s degree in public policy at Harvard’s Kennedy School of Government, that he found his passion for economics. At the Kennedy School, Björkegren met a group of development economists who were doing work he found fascinating.

“They were very techy people who were thinking analytically about how to help people who are very poor,” Björkegren said. “Once I saw this community and got a sense of what they were doing, I knew that’s what I wanted to do. So I started a Ph.D. in economics at Harvard. Because I came from the hard sciences I think I approach things a little more like an engineer. I’m good at programming and I’m good at making use of big data sets.”

Currently, he’s using data from billions of mobile phone transactions to shed new light on key aspects of economic development in Africa.

Mobile phone use in developing nations has skyrocketed over the last decade or so. It’s estimated that mobile phone subscriptions in developing countries went from around 250 million in 2000 to 4.5 billion in 2011. Mobile phone carriers maintain data on transactions across the network — calls, the costs of those calls, and other information. Björkegren uses those data — fully anonymized — to better understand network effects in developing economies.

Network effects emerge when the value of a good or service increases as more people adopt the service. Telephones are a classic example. The value of owning a telephone increases each time a new person buys a phone, because it adds one more person who can receive calls. “There’s been a lot of theory about what policies you should use to try to grow these networks and help them reach an optimal size,” Björkegren said. “But it’s not clear in general how effective these policies are or what one should do.”

Björkegren looked at activity across the main mobile phone network in Rwanda over a four-and-a-half year period — 5.3 billion transactions in total. By analyzing those data, he was able to estimate the value of each node in the network and evaluate possible incentives for helping the network to grow. He showed a substantial benefit to an incentive program that subsidizes access to mobile phone networks in rural areas.

In addition to his research work, Björkegren hasn’t forgotten his days teaching high school in Texas. He takes teaching very seriously and says he’s happy to be at a place like Brown where classroom instruction is more than just an afterthought.

“When I interviewed here, the way that people talked about their students was different,” he said. “You could tell that people were excited about their students. I found that really exciting.”