Research > Research Themes > Networks in Population

PSC Researchers identified with this theme are listed below.

Most work in population involves individual-level data and models, with aggregation to the population level by summation or averaging. Network and social interaction processes have emerged as a unifying theme in population studies to integrate previously disjoint areas of research. This integration has been facilitated by recent progress in statistical network models and tools for the analyses of network data (e.g., by M. Morris and M. Handcock at Washington), theoretical and empirical advances in understanding human behavior in the context of social interactions, a revision of the classical epidemiological model of disease diffusion that is cognizant of the role of social and sexual networks for the spread of many epidemics such as HIV/AIDS (Morris, et al.), the availability of large-scale longitudinal data on social and sexual networks, and computational methods for analyzing human behavior in interacting contexts.

Researchers at the PSC have been at the forefront of both theoretical work and collecting and analyzing data on social networks. Kohler’s Fertility and Social Interaction was a landmark study. Women who adopt contraception tend to be embedded in social networks in which other women are contraceptive adopters; and this is not simply a function of homophily with respect to observable social characteristics such as education. This suggests a process of social diffusion, although the cause-and-effect as between network structure and behavioral outcome can be ambiguous, since network structure need not be exogenous with respect to unobserved characteristics of network members. The mechanism by which social networks impinge on behavior is not apparent a priori. It may be social learning, in which networks are conduits of information, or social influence, in which networks are the locus of social norms and normative sanctions. Kohler used data from Watkins’ Kenyan Diffusion and Ideational Change Project to differentiate between social learning and social influence. These data contain information not only on the proportion of network partners who use contraception, but also on the density of the networks–who knows whom? Where market activity was comparatively high, social networks were a source of social learning, where market activity was comparatively low, social influence was ascendant. Their Malawi project (with Behrman) has been organized around network research, and has led to a research source with many of the network features of AddHealth; e.g., the work by Kohler with S. Helleringer tracing the AIDS epidemic on Likoma Island as a function of a census of network sexual ties and measures of seroprevalence. These data have attracted the research interest of De Paula, who had done previous theoretical and empirical work on networks and contagion (Union desertion in the Civil War). Additional relevant work: Postlewaite, on the role of social skills in fostering “connectedness” in economic activity, and Mutz, on the role of social trust in communication. Both Ríos-Rull and Todd (collaborating with De Paula) have strong computational skills and interests in network processes.

Vision for future. The PSC is very well positioned to make important contributions to this emerging research in the area of networks and population. We have foundational researchers such as Kohler and Watkins. We have recruited Yakubovich who has collaborated with M. Granovetter and has studied weak versus strong ties in networks in markets into the PSC, so that we have a strong axis on network theory from economic, sociological and demographic perspectives. The opportunity for creating even more interaction is apparent, and there are ongoing projects in addition to those above that can benefit from this emphasis (e.g., Chao and Pauly’s research on spillover effects of AIDS sickness in communities on other workers and businesses). We will continue investment in the Linux computing clusters that allow analyses of complex behaviors in interacting populations; and some seminar activities of the development core will be devoted to publicizing network methods in population studies and forging linkages among researchers.

PSC Research Associates involved in this area of research:
Behrman, Chao, DePaula, Kohler H-P, Mutz, Pauly, Postlewaite, Ríos-Rull, Todd, Watkins, Yakubovich

PSC Students interested in this research area:
Appiah-Yeboah, Chae, Grant, Margolis