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Concept: Homophily


Homophily, the tendency of individuals to associate with others who share similar traits, has been identified as a major driving force in the formation and evolution of social ties. In many cases, it is not clear if homophily is the result of a socialization process, where individuals change their traits according to the dominance of that trait in their local social networks, or if it results from a selection process, in which individuals reshape their social networks so that their traits match those in the new environment. Here we demonstrate the detailed temporal formation of strong homophily in academic achievements of high school and university students. We analyze a unique dataset that contains information about the detailed time evolution of a friendship network of 6,000 students across 42 months. Combining the evolving social network data with the time series of the academic performance (GPA) of individual students, we show that academic homophily is a result of selection: students prefer to gradually reorganize their social networks according to their performance levels, rather than adapting their performance to the level of their local group. We find no signs for a pull effect, where a social environment of good performers motivates bad students to improve their performance. We are able to understand the underlying dynamics of grades and networks with a simple model. The lack of a social pull effect in classical educational settings could have important implications for the understanding of the observed persistence of segregation, inequality and social immobility in societies.

Concepts: Sociology, Networks, Social capital, Social network, Network theory, Network science, Mathematical sociology, Homophily


Programs that serve transition-age youth with serious mental health conditions typically reside in either the child or the adult system. Good service provision calls for interactions among these programs. The objective of this research was to discover programmatic characteristics that facilitate or impede collaboration with programs serving dissimilar age groups, among programs that serve transition-age youth. To examine this “cross-age collaboration,” this research used social network analysis methods to generate homophily and heterophily scores in three communities that had received federal grants to improve services for this population. Heterophily scores (i.e., a measure of cross-age collaboration) in programs serving only transition-age youth were significantly higher than the heterophily scores of programs that served only adults or only children. Few other program markers or malleable program factors predicted heterophily. Programs that specialize in serving transition-age youth are a good resource for gaining knowledge of how to bridge adult and child programs.

Concepts: The Age, Sociology, Program, Adult, Social network, Program management, Network theory, Homophily


Minimal attention has been paid to what factors may predict peer nomination or how peer nominations might exhibit a clustering effect. Focusing on the homophily principle that “birds of a feather flock together,” and using a social network analysis approach, the authors investigated how certain student- and/or school-based factors might predict the likelihood of peer nomination, and the clusters, if any, that occur among those nominations.

Concepts: Scientific method, Sociology, Bird, Social network, Network theory, Network science, Complex network, Homophily


Much empirical evidence shows that individuals usually exhibit significant homophily in social networks. We demonstrate, however, skill complementarity enhances heterophily in the formation of collaboration networks, where people prefer to forge social ties with people who have professions different from their own. We construct a model to quantify the heterophily by assuming that individuals choose collaborators to maximize utility. Using a huge database of online societies, we find evidence of heterophily in collaboration networks. The results of model calibration confirm the presence of heterophily. Both empirical analysis and model calibration show that the heterophilous feature is persistent along the evolution of online societies. Furthermore, the degree of skill complementarity is positively correlated with their production output. Our work sheds new light on the scientific research utility of virtual worlds for studying human behaviors in complex socioeconomic systems.

Concepts: Scientific method, Sociology, Science, Research, Empiricism, Empirical, Empirical research, Homophily