Dynamics and evolution of biological and social networks

Opportunity and choice in social networks

Author: Matteo Marsili, Abdus Salam ICTP.

Names and affiliation of other authors:
Paolo Pin, Abdus Salam ICTP, Trieste Italy
Silvio Franz, LPTMS, Orsay, Paris, France

Oral presentation

The human tendency to establish relations with indivuduals of the same type -- called imbreeding homophily -- has been related either to a biased choice behavior or to a bias in opportunities. We propose an indicator to distinguish between these effects for minority groups and test it on data on US marriages and
friendships in US schools. We find that: for what concerns education i) opportunity--based homophily is much stronger than choice--based homophily and ii) they are both remarkably stationary in time; concerning race iii) school friendships do not exhibit opportunity-based homophily, while marriages do, iv) choice-based homophily is much stronger for marriages than for friendships and v) these effects vary widely across race.
We also discuss how, withing the Schelling model of residential segregation, choices influence opportunities. Segregation in this model takes place via a coarsening process which can be characterized quantitatively using tools of statistical physics.

Dynamics and evolution of biological and social networks. February 18-20th, 2008. Mallorca, Spain.