Quantifying social segregation in large-scale networks

Abstract

We present a measure of social segregation which combines mobile phone data and income register data in Oslo, Norway. In addition to measuring the extent of social segregation, our study shows that social segregation is strong, robust, and that social networks are particularly clustered among the richest. Using location data on the areas where people work, we also examine whether exposure to other social strata weakens measured segregation. Lastly, we extend our analysis to a large South Asian city and show that our main results hold across two widely different societies.

Figure 1

Economic segregation in telecommunication. The figure illustrates economic segregation in telecommunication in Oslo. Panel (a) shows the average income rank of receivers by the income percentile of the sender, as well as local linear smoothing of the relationship. Within tower communication is disregarded to exclude within household communication. Panel (b) shows a binned scatter plot with the number of communication events between cell phone towers against the absolute value of difference in log income between the two. Z includes controls for geographical distance between two cell towers (up to fourth polynomial), the income level of sending and receiving tower, total tower traffic level and expected tower traffic level.

Figure 2

Daytime exposure to other social strata and segregation. Panel (a) shows the relationship between own income and average income at the daytime tower. Exposure to other socioeconomic groups is measured as the absolute deviation from this regression line. Panel (b) shows the distribution of exposure and the marginal effect of income differences on total communication intensity as a function of exposure.

Figure 3

Clustering in networks. The figure shows the distribution of the communication weighted clustering coefficient, in random samples of 100 towers, as well as the clustering coefficient observed in the poorest (red line—to the left) and richest (blue line—to the right) 100 towers.

Figure 4

Segregation in the Asian data: average income of sender and receiver. The figure corresponds to Fig. 1a. The figure shows the average income percentile of receivers by the income percentile of the sender as well as local linear smoothing of the relationship. Within tower communication is disregarded.