Modelling Diffusion through Statistical Network Analysis: A Simulation Study

Abstract

The study of international relations by definition deals with interdependencies among countries. One form of interdependence between countries is the diffusion of countrylevel features, such as policies, political regimes, or conflict. In these studies, the outcome variable tends to be categorical, and the primary concern is the clustering of the outcome variable among connected countries. Statistically, such clustering is studied with spatial econometric models. This paper instead proposes the use of a statistical network approach to model diffusion with a binary outcome variable. Using statistical network instead of spatial econometric models allows for a more natural specification of the diffusion process, assuming autocorrelation in the outcomes rather than the corresponding latent variable, and it simplifies the inclusion of temporal dynamics, higher level interdependencies and interactions between network ties and country-level features. In our simulations, the performance of the Stochastic Actor-Oriented Model (SAOM) estimator is evaluated. Our simulation results show that spatial parameters and coefficients on additional covariates in a static binary spatial autoregressive model are accurately recovered when using SAOM, albeit on a different scale. To demonstrate the use of this model, the paper applies the model to the international diffusion of same-sex marriage.