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Search in the Formation of Large Networks: How Random are Socially Generated Networks?

Jackson, Matthew O. and Rogers, Brian W. (2005) Search in the Formation of Large Networks: How Random are Socially Generated Networks? Social Science Working Paper, 1216. California Institute of Technology , Pasadena, CA. (Unpublished)

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We present a model of network formation where entering nodes find other nodes to link to both completely at random and through search of the neighborhoods of these randomly met nodes. We show that this model exhibits the full spectrum of features that have been found to characterize large socially generated networks. Moreover, we derive the distribution of degree (number of links) across nodes, and show that while the upper tail of the distribution is approximately "scale-free," the lower tail may exhibit substantial curvature, just as in observed networks. We then fit the model to data from six networks. Besides offering a close fit of these diverse networks, the model allows us to impute the relative importance of search versus random attachment in link formation. We find that the fitted ratio of random meetings to search-based meetings varies dramatically across these applications. Finally, we show that as this random/search ratio varies, the resulting degree distributions can be completely ordered in the sense of second order stochastic dominance. This allows us to infer how the relative randomness in the formation process affects average utility in the network.

Item Type:Report or Paper (Working Paper)
Jackson, Matthew O.0000-0001-9846-4249
Additional Information:We gratefully acknowledge financial support under NSF grant SES-0316493, the Lee Center for Advanced Networking, and a SISL/IST fellowship. We thank David Alderson, Hawoong Jeong, Sanjeev Goyal, Marco van der Leij, and Jose Luis Moraga-Gonzalez for making data available. We thank Steven Durlauf for a helpful discussion of the paper and Antoni Calvo-Armengol, Matthias Dahm, Dunia Lopez-Pintado, Fernando Vega-Redondo, and Duncan Watts for helpful comments and conversations.
Group:Social Science Working Papers
Funding AgencyGrant Number
Caltech Lee Center for Advanced NetworkingUNSPECIFIED
Caltech Social and Information Sciences LaboratoryUNSPECIFIED
Subject Keywords:Networks, Network Formation, Power Laws, Scale-Free Networks, Small Worlds, Search
Series Name:Social Science Working Paper
Issue or Number:1216
Classification Code:JEL: D85, A14, C71, C72
Record Number:CaltechAUTHORS:20170809-094225745
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:80004
Deposited By: Hanna Storlie
Deposited On:09 Aug 2017 18:48
Last Modified:03 Oct 2019 18:26

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