The role of endogenous network mechanisms for ethnic friendship segregation in classrooms.

This thesis studies the interrelation of ethnic homophily and three endogenous network processes as mechanisms related to ethnic segregation of friendship networks in classrooms. Stochastic actor oriented models are applied to a German and a Swedish sample of several classrooms to investigate in-group tendencies in transitivity, reciprocity and centrality. Findings from a hierarchical analysis of the dynamics in 33 classrooms (HSAOM) from the German sample reveal that dyadic homophily can only be found for non-native pupils. Accounting for homophily in transitivity reveals natives having a small tendency for embedded ties to the out-group, while non-natives show no differences of transitivity to in- or out-group. The data suggest that homophily for nonnatives might be driven by the dissolution of one-sided not-embedded friendship nominations after the first observation. HSAOM are used to analyse the Swedish sample of 194 classrooms in order analyse the role of reciprocity for the creation and maintenance of pupils' in- and out-group friendships. The results show similar tendencies for one sided and reciprocal homophily in friendship creation. While for friendship maintenance homophily is apparent in asymmetric relations, reciprocated friendships are more often dissolved within groups than between. Lastly, stochastic actor oriented models applied to separately analyse a subset of 64 classrooms from the Swedish CILS4EU data and the results are subsequently used for data-driven simulations in order to investigate how structural homophily mechanisms can have lead to the segregation of the first network observations. Results from the meta-analysis of the classroom models indicate no clear tendencies of homophily in either reciprocity, transitivity or centrality. However, accounting for these mechanism in data-driven agent based simulations provides give some insights about the emergence of segregation. The presented research projects underline that endogenous network mechanisms represent different social situations for pupils' choices about friendships to their ethnic in- and out-group. Accounting for these, helps to understand which relational structures between pupils from different backgrounds could be encouraged to avoid or reduce segregation.