Willing to Learn But Ready to Move: An Extension of Schelling’s ModelWilling to Learn But Ready to Move: An Extension of Schelling’s ModelBruno Abrahao Bruno Abrahao Zhiyuan SongZhiyuan Song Bogdan StateBogdan StateComputer Science Dept.Computer Science Dept. Biology Dept.Biology Dept. Sociology Dept.Sociology Dept.Cornell UniversityCornell University Stanford UniversityStanford University Stanford UniversityStanford University

IntroductionIntroduction• We study the coevolution of two networks We study the coevolution of two networks

using Agent-Based Modelling.using Agent-Based Modelling.• We extend Schelling’s model in a novel We extend Schelling’s model in a novel

direction: the interaction of social and direction: the interaction of social and residential networks.residential networks.

• Do social networks act to exacerbate or Do social networks act to exacerbate or attenuate segregation outcomes?attenuate segregation outcomes?

Prospective FindingsProspective Findings• As expected, As expected, network densitynetwork density (more (more

opportunity for contact) reduces opportunity for contact) reduces preference for homogeneity and preference for homogeneity and ameliorates segregation outcomes (as ameliorates segregation outcomes (as measured by a dissimilarity index).measured by a dissimilarity index).

• The effect of network density is greater The effect of network density is greater with high initial preferences for with high initial preferences for homogeneity.homogeneity.

• Surprisingly, Surprisingly, turnoverturnover in friendship in friendship formation does not appear to have a formation does not appear to have a substantial effect.substantial effect.• Uses Agent-Based Simulations to Uses Agent-Based Simulations to

examine effects of various kinds of social examine effects of various kinds of social networks on segregation outcomes.networks on segregation outcomes.

MethodologyMethodologySchelling-like residential gridSchelling-like residential grid: : • Actors of two different categories.Actors of two different categories.• Minimum thresholds (residential Minimum thresholds (residential

preferences);preferences);• Move if preferences unsatisfied. Move if preferences unsatisfied. Preferences determinedPreferences determined by by contact contact

hypothesis:hypothesis:• meaningful contact by means of social meaningful contact by means of social

ties.ties.• learning according to learning according to urn modelurn model from from

friendship circle.friendship circle.Social tiesSocial ties formed through formed through propinquitypropinquity. . • Neighbors have higher likelihood to Neighbors have higher likelihood to

become friends.become friends.Uses fixed model of social network Uses fixed model of social network

topologytopology, to facilitate observation of , to facilitate observation of outcomes:outcomes:

• Regular random graph preserved by Regular random graph preserved by linking neighbors with fixed probability.linking neighbors with fixed probability.

• Ties have exponentially-decaying Ties have exponentially-decaying lifetimes.lifetimes.

MechanismMechanism

• Extension of examination to more realistic Extension of examination to more realistic social network structures (e.g. scale-free social network structures (e.g. scale-free networks).networks).

• Application of model to real-world data Application of model to real-world data concerning segregation outcomes, concerning segregation outcomes, residential or otherwise.residential or otherwise.

Future WorkFuture Work