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Community structure in Congressional cosponsorship networks

Zhang, Y. and Friend, A. J. and Traud, Amanda L. and Porter, Mason A. and Fowler, James H. and Mucha, Peter J. (2008) Community structure in Congressional cosponsorship networks. Physica A, 387 (7). pp. 1705-1712. ISSN 0378-4371. doi:10.1016/j.physa.2007.11.004.

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We study the United States Congress by constructing networks between Members of Congress based on the legislation that they cosponsor. Using the concept of modularity, we identify the community structure of Congressmen, as connected via sponsorship/cosponsorship of the same legislation, to investigate the collaborative communities of legislators in both chambers of Congress. This analysis yields an explicit and conceptually clear measure of political polarization, demonstrating a sharp increase in partisan polarization which preceded and then culminated in the 104th Congress (1995-1996), when Republicans took control of both chambers. Although polarization has since waned in the U.S. Senate, it remains at historically high levels in the House of Representatives.

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Zhang, Y.0000-0002-9463-3970
Additional Information:© 2007 Elsevier Ltd All rights reserved. Received 14 August 2007; revised 21 October 2007. Available online 9 November 2007. PACS classification codes: 89.75.-k; 89.65.-s We thank Thomas Callaghan, Diana Chen, Aaron Clauset, Justin Howell, Eric Kelsic, Tom Maccarone, and Mark Newman for useful discussions. We also thank an anonymous referee for useful comments on an earlier version of this manuscript. YZ was funded by Caltech’s SURF program; AJF (VIGRE grant) and ALT (NSF HRD-0450099) were funded by the NSF; MAP was funded by the Gordon and Betty Moore Foundation through Caltech’s Center for the Physics of Information (where he was a postdoc during much of this research); and PJM was supported from start-up funds provided by the Institute for Advanced Materials and the Department of Mathematics at the University of North Carolina at Chapel Hill. We obtained the committee data from the web site of the House of Representatives Office of the Clerk.
Funding AgencyGrant Number
Summer Undergraduate Research Foundation, CaltechUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
University of North Carolina at Chapel HillUNSPECIFIED
Subject Keywords:Complex networks; Social networks; Community structure; Modularity
Issue or Number:7
Record Number:CaltechAUTHORS:20090731-102747667
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14756
Deposited By: Ruth Sustaita
Deposited On:20 Aug 2009 21:21
Last Modified:08 Nov 2021 23:14

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