The Structure and Stability of Lobbying Networks in Washington.

In this paper, we use data from 499,838 semiannual reports filed under the Lobbying Disclosure Act (LDA) of 1995 to investigate the degree to which networks of lobbyists are linked with each other or operate independently as cliques, and to measure the stability of network characteristics over time. Each lobbying network is linked by individuals who report lobbying activity in one of 77 government-defined issue areas listed on LDA reports. For each of 32,045 lobbyists who have registered in any six-month reporting period from 1998 to 2007, we use social network analysis (SNA) techniques to estimate the centrality of each issue area. The time-series nature of our data set allows us to assess the dynamics of issue area centrality over time. We find that lobbying networks are remarkably stable over time, though we identify a few notable outliers that indicate that events outside the lobbying networks can affect their basic structure. Further, for each issue area, we calculate lobbyists' specialization and the proportion of for-hire contract lobbyists, and find that both specialization and contract lobbying are highly correlated to lobbying network centrality. ..PAT.-Unpublished Manuscript [ABSTRACT FROM AUTHOR]