Friendship Networks

19 Pages Posted: 19 Oct 2006

See all articles by Jan K. Brueckner

Jan K. Brueckner

University of California, Irvine - Department of Economics; CESifo (Center for Economic Studies and Ifo Institute)


This paper develops a model of social networks different from those presented in the recent literature. In contrast to existing models, the level of investment in link formation is a continuous decision variable, and links form stochastically rather than deterministically, with the probability depending on the noncooperative investment choices of both parties. Since the network structure is then stochastic rather than deterministic, the actual pattern of links cannot be specified, as in previous models, with the analysis focusing instead on which links are most likely to form. This alternate approach leads to a much simpler mathematical structure than in previous work. The analysis, which is couched in the context of friendship networks, shows that individual investment in friendship formation is too low. In addition, the analysis shows that, in an asymmetric setting where one individual has personal magnetism or a broad group of acquaintances, friendship links involving this attractive agent are most likely to form.

Suggested Citation

Brueckner, Jan K., Friendship Networks. Journal of Regional Science, Vol. 46, No. 5, pp. 847-865, December 2006. Available at SSRN: or

Jan K. Brueckner (Contact Author)

University of California, Irvine - Department of Economics ( email )

3151 Social Science Plaza
Irvine, CA 92697-5100
United States

CESifo (Center for Economic Studies and Ifo Institute)

Poschinger Str. 5
Munich, DE-81679

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