Network Science Study Shows How Urban Topology Influences the Formation of Social Networks and Inequality

A new study by a research team including CEU Department of Network and Data Science Professor Janos Kertesz and alumnus Johannes Wachs shows how the structural factor of urban topology plays a role in facilitating fragmentation and inequality. While it has already been proven that social networks amplify inequalities due to fundamental mechanisms of social tie formation such as homophily (befriending similar people) and triadic closure (befriending friends of friends), a paper, published by Nature Communications on February 18 by an international group of scientists, used big data from a widely-used online social network to demonstrate that a significant relationship exists between social network fragmentation and income inequality in cities and towns. Moreover, the researchers have found that the organization of the physical urban space has a stronger relationship with fragmentation than unequal access to education, political segregation, or the presence of ethnic and religious minorities.

“Social scientists are trying to understand the reason behind the persistence and growth of inequalities, and whether it is possible to create policies that could act against them. We know from earlier studies that social networks, as they emerge, not only reflect these inequalities but contribute to their robustness and persistence. Our aim with the research was to investigate if there are other components on the top of social networks that act towards stabilizing these social networks which create the robustness of inequalities,” explains Kertesz, one of the authors of the paper.

In the study entitled “Inequality is rising where social network segregation interacts with urban topology” the researchers argue that fragmentation of social networks is significantly higher in towns in which residential neighborhoods are divided by physical barriers such as rivers and/or railroads, and are relatively distant from the center of town. Also, towns in which amenities are spatially concentrated are typically more socially segregated.

“According to urban sociology research, people cannot easily build social ties when they are separated by large physical obstacles such as rivers, railways, highways or walls,” says Wachs currently at the Institute for Data, Process and Knowledge Management of Vienna University of Economics and Business and another author of the paper. “This was confirmed in our research: we could see evidence of strong physical boundaries in a city just by looking at its social network. We hypothesized - and confirm it with our findings - that if valuable ideas and information cannot float freely through a city because that city is physically fragmented, it in turn causes social fragmentation, which we will see in inequality. We clearly see how strongly geography and income inequality are related.”

The findings of the paper suggest how urban planning could be a useful point of intervention to mitigate inequalities in the long run, and how “smart city projects” that build massively on the collection and evaluation of large amounts of data should also build on social network data so that urban planning can make cities better functioning and places of better life quality.