Speaker: Mark Handcock Title: Assessing the Goodness-of-Fit of Network Models Network models are widely used to represent relational information among interacting units and the implications of these relations. In studies of social networks recent emphasis has been placed on random graph models where the nodes usually represent individual social actors and the edges represent a specified relationship between the actors. Much progress has been made on exponential family models for cross-sectional networks, and some has been made on related models for networks observed longitudinally. We present methods to assess how well estimates of network structure fit the network data on which they are based. The first such methods are based on the likelihood-ratio statistics. The second compare structural statistics of the observed data with the corresponding statistics on graphs generated from the fitted model. We apply this approach to the study of friendship relations among high school students from the National Longitudinal Study of Adolescent Health. The sizes of the networks we fit range from 71 to 2209 nodes. This is joint work with David R. Hunter and Steven M. Goodreau.