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Yves Zenou, professor of economics at the University of Stockholm, spoke about finding the key player in criminal networks on Thursday, Jan. 9, in the Social Science’s Plaza B.

Zenou is the author of two books and the co-author of countless publications detailing his research. He has been a guest professor all over the world, including Japan, Australia and Israel. His research interests include social interactions and network theory.

Jack Yu | Photography Intern
Jack Yu | Photography Intern

About 35 graduate students and faculty members came to hear Zenou speak. Through a series of calculations and formulas, Zenou detailed a structured explanation of how finding and removing one key leader in a network of criminals could lead to an eventual decrease in overall crime in a real-world setting. With a vast amount of people behind bars in the United States, Zenou suggests that his theory could lead to an eventual decrease in crime by removing that one leader, or key player from a group of criminals.

Part of Zenou’s research on criminal networks is based on positive peer effects, or rather, how one may find affirmation from one’s peers. He suggests that one is more likely to commit a crime if a peer commits a crime.

Zenou explains the network effect by suggesting that a criminal is much more likely to commit a crime if a friend of his commits a crime or spends time in jail. He has also found strong evidence in how “committing a particular crime increases the probability that an individual who has already committed the same type of crime recidivates that crime.”

“There’s no school in crime,” Zenou said. “Criminal behavior is taught by friends and peers.”

“There is a difference between network effect and peer effect. Peer effect is just an average affect, [like how] I want to see to see how much my grade is affected, I’m going to get the average grade of my roommates or classmates. Network effect, you look much more deeper, you look into all the interaction between people.”

Among the many questions that arose during his lecture, Zenou explored how much crime reduction would forgo if this key-player policy would be put into practice. Zenou says that crime reduction would depend on the size of the criminal network itself. According to his paper, “Criminal Networks: Who is the Key Player?” that he worked on together with four others, it’s stated that “compared to a policy that removes random delinquents from the network, a key player policy engenders a crime reduction that can be as large as 35 percent.”

Yet, the key criminal is not effectively the most active criminal in the network and it’s not “straightforward to determine which delinquent should be removed from the network by only observing his or her criminal activities or position in the network.” Since someone cannot be put into prison without committing a crime, authorial figures are left to other devices to target the key criminal. They can persuade them to leave the criminal group or “target [the key criminal] in a meaningful way.”

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