Friends, brokers, and transitivity: Who informs whom in Washington politics?

Why and how do groups share information in politics? Most studies of information exchange in politics focus on individual-level attributes and implicitly assume that communication between any two policy actors is independent of the larger communication network in which they are embedded. We develop a theory stating that the decision of any lobbyist to inform another lobbyist is heavily conditioned upon their mutual relationships to third par-ties. We analyze over 40,000 dyadic relationships among lobbyists, government agencies, and congressional staff using sociometric data gathered in the 1970s health and energy policy domains. The results cohere with recent findings that lobbyists disproportionately inform those with similar preferences and show in addition that political communication is transitive: holding constant the degree of preference similarity, a lobbyist is more likely to communicate with another lobbyist if their relationship is brokered by a third party.