Paraules clau:: segregation,random walk,measure,spain,census,centrality,pagerank
Resum: In this paper, we propose an intuitive way of how to measure residential segregation. Individuals are located in different nodes on a network that are interconnected through links. Each period, an individual either advances to an adjacent node or she stops moving. In this setting, the segregation index is then defined as the probability that a randomly chosen individual meets an individual of the same social group in the neighborhood where her random-walk terminates. It is shown in a dual theorem that the segregation index is as a natural generalization of the isolation index to networks and that it is proportional to the PageRank index applied by Google in order to determine the importance of web-pages. Finally, the segregation index is applied to the Spanish 2009 census tract data and compared with other prominent measures.