New Worlds of Social Network Research

to build accurate models of relational data. Carter Butts discusses the conditions under which simple distance is a major predictor of total network structure in large and spatially embedded networks. Peter Hoff sets out a generalized linear mixed effects approach to modeling social networks in which depen dence among ties is attributed to unobserved attributes of vertices, which relate preferen tially to vertices with similar attribute values. Michael Ward, Peter Hoff, and Corey Lofdahl give an extended application of Hoff's mod eling approach to international relations among Central Asian countries with specific attention given to how the analysis can be used to impute missing network linkages. Finally, Nosh Contractor and Peter Monge's chapter reviews theories and theoretical mechanisms that have been proposed to gov em the formation of relations and embeds that review in a multi-theoretical, multi-level mod eling approach focused on networks of orga nizations that compete for similar resources (adversarial networks). It is worth noting that the workshop was held in 2002 and the edited volume of papers published in 2003. Research since then has advanced along many of the fronts discussed in the papers, in particular, the statistical mod eling of networks using exponential random graph models. Nevertheless, the volume remains valuable as an overview of a wide ranging set of research concerns that com poses the field of modern social network analysis. At the same time, the Office of Naval Research got its money's worth: there were papers that specifically addressed questions driven by national security concerns and the final comments by Kathleen Carley set out a clear road map by which social network analysis could better contribute to the solution of national security problems, providing new tools and techniques of analysis and, just as important, clear understanding of their limita tions in field situations.