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How Do Friendships Form?

Bruce Sacerdote

Dartmouth College - Department of Economics; National Bureau of Economic Research (NBER)

David Marmaros

affiliation not provided to SSRN

August 2005

NBER Working Paper No. w11530

We examine how people form social networks among their peers. We use a unique dataset that tells us the volume of email between any two people in the sample. The data are from students and recent graduates of Dartmouth College. First year students interact with peers in their immediate proximity and form long term friendships with a subset of these people. This result is consistent with a model in which the expected value of interacting with an unknown person is low (making traveling solely to meet new people unlikely), while the benefits from interacting with the same person repeatedly are high. Geographic proximity and race are greater determinants of social interaction than are common interests, majors, or family background. Two randomly chosen white students interact three times more often than do a black student and a white student. However, placing the black and white student in the same freshman dorm increases their frequency of interaction by a factor of three. A traditional "linear in group means" model of peer ability is only a reasonable approximation to the ability of actual peers chosen when we form the groups around all key factors including distance, race and cohort.

Number of Pages in PDF File: 48

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Date posted: September 16, 2005  

Suggested Citation

Sacerdote, Bruce and Marmaros, David, How Do Friendships Form? (August 2005). NBER Working Paper No. w11530. Available at SSRN: https://ssrn.com/abstract=776569

Contact Information

Bruce Sacerdote (Contact Author)
National Bureau of Economic Research (NBER)
1050 Massachusetts Avenue
Cambridge, MA 02138
United States
Dartmouth College - Department of Economics ( email )
6106 Rockefeller Hall
Hanover, NH 03755
United States
603-646-2121 (Phone)
603-646-2122 (Fax)
David Marmaros
affiliation not provided to SSRN
No Address Available
Feedback to SSRN

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References:  44
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