Network scientist analyzes life's 'digital breadcrumbs'

David Lazer, an expert in social networks and their effects on politics and organizations, joins the faculty this year as an associate professor with a joint appointment in political science and computer science.

The author of two books and many journal articles, Lazer most recently published a study on cell phone usage among friends, which appeared in the Proceedings of the National Academy of Sciences. The article examined patterns of cell phone use and the proximity of one cell phone to the next, via satellite positioning technology, in attempts to correlate patterns with levels of friendship. Researchers deduced the degree of friendship by analyzing the frequency of cell phone calls and proximity of the phones.

“Friendship is something that is hard to observe because, in a deep sense, it exists in someone’s head,” said Lazer, formerly a professor at Harvard’s Kennedy School of Government. “People can be friends with someone they haven’t seen for years or rarely talk with.”

In his study, conducted with Nathan Eagle of the Santa Fe Institute in New Mexico and colleague Sandy Pentland of the Massachusetts Institute of Technology, the cell phone was used to look for patterns, or “behavioral signatures,” exhibited by friends. These include the number of calls made, and the nearness of cell-phone users to one another. The study concluded, with 95 percent accuracy, that patterns of use and proximity could predict which of the study volunteers would identify themselves as friends.

Now at Northeastern, Lazer plans to expand his research scope by tracking what he terms “digital breadcrumbs”—like those monitored in the cell-phone study—to analyze data on everything from human interactions during political election seasons to behavioral patterns during flu season, he says.

Working with the media lab, he also plans to research telephone data to better understand the structures of society, and who talks with whom, he notes.

Lazer will continue to direct Harvard’s Program on Networked Governance, which fosters research on the interconnectedness of separate governmental units and provides a forum to discuss challenges related to traditional notions of hierarchical, top-down government.

Lazer will work with Northeastern’s Center for Complex Network Research and has extensive ties with distinguished physics professor and network scientist Albert-László Barabási, who leads the center. He coauthored “Computational Social Science” with Barabási.  The article appeared in the February issue of Science.

“In the Science article,” Lazer says, “we looked at how the social sciences will change due to the availability of amazing new data, from e-mail, to many, many other sources of data available on the Internet.”

The article notes that the capacity to collect and analyze tremendous amounts of data has transformed fields such as physics and biology, but that computational social science fields, such as economics, sociology and political science, have only begun to leverage the capacity to collect and analyze data “with an unprecedented breadth and depth and scale.”

“We’re trying to build a bridge between old methods (of data collection) and new,” Lazer said. “The social sciences need to change in reaction to the availability of data.”

Major news and information outlets, including “60 Minutes,” and Nature and Forbes magazines, have cited Lazer’s research on the power of technology.

He was quoted in a 2009 Nature article, “Search engines provide information about epidemics,” and the 2008 Forbes article, “Obama’s Machine,” on the power of technology. His work was also cited on the April 2, 2007 broadcast of “60 Minutes,” in a segment titled “Not so Perfect Match.” Here, his research into the use of database searches in criminal investigations was referenced.

With an extensive research background, and new prospects ahead, Lazer said he is excited to join Northeastern. He cited Barabási’s well-known work,  and noted he hopes to add to the university’s international reputation in network science.

—Susan Salk