Characterizing social network homophily and residential mobility through analysis of call detail records
Researchers: Samuel Heroy, Neave O’Clery
Description of work
Worldwide, people are moving to cities—by 2050, 2 out of every 3 people will live in cities or urban centers, a statistic that is already exceeded in Latin America and other regions1. This dramatic worldwide urbanization trend poses both opportunities for and challenges to inclusive development. Cities are engines of productivity, diversity, and economic growth, but it can also be argued that as they get larger, they get more unequal and segregated. While the largest cities have disproportionately higher incomes, they tend to also have disproportionately higher housing costs, often pushing low/middle income residents away from centers of economic activity (Sarkar 2018) , and indeed leading to higher income inequality (Cottineau et al. 2018).
This relationship between inequality and city size underscores the importance of social capital to inclusive growth. Social capital can be defined as “a person’s social characteristics – including social skills, charisma, and the size of [their] Rolodex – which enables [them] to reap market and non-market returns from interactions with others” (Glaeser, Laibson, and Sacerdote 2002). People regularly access economic opportunities through the capacity of their collective social networks, and then often rely on core social networks in times of difficulty. Moreover, telecommunications data demonstrates that people in highly prosperous areas have on average more spatially diverse communication patterns—they have repeated contacts with individuals in many separate locations—whereas people in less prosperous areas tend to limit their communications to spatially redundant and closely-knit cores (Eagle 2010).
As cities continue to grow, we can expect that city dynamics will depend heavily on residential mobility. For any household, the decision to move is inherently complicated and dependent on both social and economic factors. In one endeavour, we will explore the relationship between social networks, socioeconomic class, and residential mobility. That is, we will investigate how social network properties tend to influence one’s propensity to move, the effect of moving on one’s social network, and how these relationships are facilitated by income.
Aims and research questions
A question of importance is: as cities grow, and potentially experience higher income segregation (alignment of neighbourhood residential composition with income), what is the effect on social network characteristics? The second portion of our study examines what factors influence the stratification of communication patterns (social networks) along socioeconomic lines. In particular, we will examine whether and to what extent this social network stratification is influenced by residential socioeconomic segregation and/or socioeconomically stratified urban travel patterns.
In particular, we will study these relationships using data from Colombia, and pay special attention to the unique factors driving urbanization, residential mobility, and class stratification in Colombian cities. Moreover, our aims will be duly scientific and policy-oriented, with an emphasis on generating large-scale data that has importance to current urban policy issues in Colombia.
In our study, we will use CDR to approach the following questions:
- Does living in a socioeconomically less isolated area (e.g. closer to neighbourhoods of different socioeconomic class) lead to having a more socioeconomically diverse social network? Does living in a less socioeconomically isolated area make you more likely to interact with different socioeconomic classes?
- Is having a more socioeconomically integrated/diverse travel patterns linked with having a more socioeconomically diverse social network? That is, does traveling to areas of varying socioeconomic class increase your propensity to interact with different socioeconomic class?
- How do these two relationships vary across different income levels?