Modelling the evolution of a bipartite network - Peer referral in interlocking directorates

Abstract in Undetermined
A central part of relational ties between social actors is constituted by shared affiliations and events. The action of joint participation reinforces personal ties between social actors as well as mutually shared values and norms that in turn perpetuate the patterns of social action that define groups. Therefore the study of bipartitenetworks is central to social science. Furthermore, the dynamics of these processes suggests that bipartitenetworks should not be considered static structures but rather be studied over time. In order to model the evolution of bipartitenetworks empirically we introduce a class of models and a Bayesian inference scheme that extends previous stochastic actor-oriented models for unimodal graphs. Contemporary research on interlockingdirectorates provides an area of research in which it seems reasonable to apply the model. Specifically, we address the question of how tie formation, i.e. director recruitment, contributes to the structural properties of the interlockingdirectoratenetwork. For boards of directors on the Stockholm stock exchange we propose that a prolific mechanism in tie formation is that of peerreferral. The results indicate that such a mechanism is present, generating multiple interlocks between boards.