Title: 

 Heider vs Simmel: Comparing Generative Models of Network Formation


Abstract: 

 Heider's balance theory has been a cornerstone of structural explanations and explorations of network dynamics.  Most frequently, Heider's theory is interpreted as inducing reciprocated and transitive ties among nodes in a graph.  Empirical work consistently shows that these structural features (reciprocity and transitivity) occur in naturally emergent networks more often than we would expect under standard random graph assumptions, a result that is often used to claim that Heider's model is a valid representation of the real world.  The problem is, any simulation of a generative model based on Heider's principles almost invariably leads to a degenerate result of complete graphs or components. 50 years prior to Heider, Simmel proposed a triadic model of social analysis, one that has distinct parallels with Heider but has a structural/sociological rather than psychological base.  Simmel's model, while it also explains the relatively frequent existence of reciprocated and transitive ties, is based on a simpler premise.  I will provide both empirical evidence for Simmel's alternate view of the social world and compare the dynamics of Heiderian and Simmelian structures in a generative model of tie formation.


Bio:

 David Krackhardt is Professor of Organizations at the Heinz School of Public Policy and Management and the Graduate School of Industrial Administration, Carnegie Mellon University. Prior appointments include faculty positions at Cornell's Graduate School of Management, the University of Chicago's Graduate School of Business, INSEAD (France) and the Harvard Business School. He received a BS degree from the Massachusetts Institute of Technology and a PhD from the University of California, Irvine.

 Over the past 15 years, his research has focused on how the theoretical insights and methodological innovations of network analysis can enhance our understanding of how organizations function. He pioneered the concept of "cognitive social structures", wherein individuals provide their perceptions of the entire network in which they are embedded. He empirically has related these perceived structures to turnover, reputations and power in organizations. Another interest of his has been in developing methodologies for better understanding networks and their implications. His contributions in this arena include adapting the quadratic assignment procedure to multiple regression analyses of network data. In addition, he has developed methods drawing from graph theory for studying the shape and structure of organizations as a whole.

 His published works have appeared in a variety of journals in the fields of psychology, sociology, anthropology and management. His current research agenda includes developing models of diffusion of controversial innovations, exploring and testing visual representations of networks, identifying effective leverage points for organizational change, and exploring the roles of Simmelian (super-strong) ties in organizations. Prof. Krackhardt was born in 1950 in Massachusetts. He is married with three children.