Network Inequality through Preferential Attachment, Triadic Closure, and Homophily
For researchers studying inequality in social networks, this work provides a unified framework to understand how three key linking mechanisms jointly produce group disparities, though the findings are based on synthetic simulations and one empirical case.
The paper introduces PATCH, a network growth model combining preferential attachment, homophily, and triadic closure, and shows through simulations that triadic closure amplifies degree inequality but reduces segregation and between-group disparities. Applied to 50 years of collaboration and citation networks, PATCH accounts for persistent gender disparities by modeling the interplay of these mechanisms.
Inequalities in social networks arise from linking mechanisms, such as preferential attachment (connecting to popular nodes), homophily (connecting to similar others), and triadic closure (connecting through mutual contacts). While preferential attachment mainly drives degree inequality and homophily drives segregation, their three-way interaction remains understudied. This gap limits our understanding of how network inequalities emerge. Here, we introduce PATCH, a network growth model combining the three mechanisms to understand how they create disparities among two groups in synthetic networks. Extensive simulations confirm that homophily and preferential attachment increase segregation and degree inequalities, while triadic closure has countervailing effects: conditional on the other mechanisms, it amplifies population-wide degree inequality while reducing segregation and between-group degree disparities. We demonstrate PATCH's explanatory potential on fifty years of Physics and Computer Science collaboration and citation networks exhibiting persistent gender disparities. PATCH accounts for these gender disparities with the joint presence of preferential attachment, moderate gender homophily, and varying levels of triadic closure. By connecting mechanisms to observed inequalities, PATCH shows how their interplay sustains group disparities and provides a framework for designing interventions that promote more equitable social networks.