Día/hora: MIÉRCOLES 16/03 de 14:30 a 15:30h.

Lugar: Seminario del Dpto. de Teoría e Historia Académica (3ª planta)

Ponente: Arnold Polanski

                Título: Homophily, Influence, and Integration: The Weakness of Weak Ties

Autores: Arnold Polanski (University of East Anglia) y Fernando Vega Redondo (Bocconi University & IGIER)

 

Abstract: We propose a model where agents with stochastic initial beliefs undergo a learning process à la De Groot (1974) for some given (possibly finite) number of rounds. We focus on an equilibrium notion that endogenizes the influence matrix by postulating that the weight an agent attributes to each of her neighbors is proportional to the correlation of their final (stochastic) beliefs. Our preferred motivation for this condition derives from the well-documented phenomenon of homophily, i.e., the tendency of individuals who behave or think similarly to “flock together."

First we establish that an equilibrium influence matrix always exists and characterize it for some benchmark cases. Then we show that a certain notion of link support (reminiscent of, but very different from, clustering) provides a key basis to understand the specific strength of different links. This provides an interesting twist to Granovetter’s (1973) celebrated claim that strong links tend to be “weak," i.e. informationally redundant. In our case, where behavior and social influence are jointly co-determined, strong links are crucial to attain social integration. From this viewpoint, therefore, valuable links require support, i.e. redundancy. The relevance of the issue is illustrated through the study of how additional connections may overcome social fragmentation.