Daniel Carpenter and Kevin Esterling and I re-examined the wonderful Laumann- Knoke data set from The Organizational State of health and energy lobbying networks from the 1980s, studying the inter-relationship between network structure and access in Washington DC. Our papers found that weak ties were especially important in determining information flows (1), but that in domains where information was particularly in demand strong ties were more important (2). Finally (3), we studied the structure of inter-lobbyist relationships, focusing on the role of micro-level brokerage within the network.

(1) Daniel Carpenter, Kevin Esterling and David Lazer, "Strength of Weak Ties in Lobbying Networks: Evidence from Health-Care Politics in the United States," Journal of Theoretical Politics, October 1998, 417-444.

(2) Daniel Carpenter, Kevin Esterling and David Lazer, "The Strength of Strong Ties:  A Model of Contact-Making in Policy Networks with Evidence from the U.S. Health Politics," Rationality and Society, November 2003.

(3) Daniel Carpenter, Kevin Esterling and David Lazer, "Friends, Brokers and Transitivity: Who Informs Whom in Washington Politics?" Journal of Politics, February 2004.

**(For any of the above articles without a link, please email david_lazer(at)harvard.edu for a PDF or hardcopy)