California Center for Population Research

Network-based strategies and competencies are probably even more important in poor societies with limited means of communication and less effective formal structures than in developed economies. And they often deal with life and death matters. This paper presents lessons from and insights about the nature of and the impacts of informal social networks in reducing fertility and coping with HIV/AIDS in Kenya and Malawi based on analyses of quantitative longitudinal data and qualitative data that the authors and their collaborators have been collecting and analyzing for over a decade. Specific lessons include the relevance of social networks and informal interactions for many different domains related to health – and thus life and death – in developing countries, the importance of accounting for the endogeneity of network partners in analyzing network effects, that networks are important even with control for endogeneity, that network effects may be nonlinear, that there may be multiple equilibria, that which networks may either reinforce the status quo or help diffuse new options and behaviors, that both the context (e.g., the degree of market development) and the density of networks matter (possibly interactively), and that multiple approaches, including both qualitative and quantitative analyses, can be informative in providing more in-depth understanding of what networks do and how they function.