Researchers use social networks to find the harbingers of new restaurants and higher rents.

By Nathan Collins

Street life is seen in the DUMBO section of Brooklyn, an area that is experiencing rapid gentrification. (Photo: Spencer Platt/Getty Images)

Depending on whom you ask, gentrification is either damaging, not so bad, or maybe even good for the low-income people who live in what we euphemistically call up-and-coming neighborhoods. Either way, it’d be nice for everybody to know which neighborhoods are going to get revitalized/eviscerated next. Now, computer scientists think they’ve found a way to do exactly that: Using Twitter and Foursquare, map the places visited by the most socially diverse crowds. Those, it turns out, are the most likely to gentrify.

Led by University of Cambridge graduate student Desislava Hristova, the researchers began their study by mapping out the social network of 37,722 Londoners who posted Foursquare check-ins via Twitter. Two people were presumed to be friends—connected on the social network—if they followed each other’s Twitter feeds. Next, Hristova and her colleagues built a geographical network of 42,080 restaurants, clubs, shops, apartments, and so on. Quaint though it may seem, the researchers treated two places as neighbors in the geographical network if they were, in fact, physically near each other. The team then linked the social and geographical networks using 549,797 Foursquare check-ins, each of which ties a person in the social network to a place in the geographical one.

Gentrification doesn’t start when outsiders move in; it starts when outsiders come to visit.

Using the network data, the team next constructed several measures of the social diversity of places, each of which helps distinguish between places that bring together friends versus strangers, and to distinguish between spots that attract socially diverse crowds versus a steady group of regulars. Among other things, those measures showed that places in the outer boroughs of London brought together more socially homogenous groups of people—in terms of their Foursquare check-ins, at least—compared with boroughs closer to the core.

But the real question is what social diversity has to do with gentrification. To measure that, the team used the United Kingdom’s Index of Multiple Deprivation, which takes into account income, education, environmental factors such as air quality, and more to quantify the socioeconomic state of affairs in localities across the U.K., including each of London’s 32 boroughs.

The rough pattern, according to the analysis: The most socially diverse places in London were also the most deprived. This is about the opposite of what you’d expect, based on social networks studied in isolation from geography, which indicates that, generally, the people with the most diverse social networks are the most prosperous.

What drives that difference? The wealthiest places and the most deprived tend to be more socially cohesive—that is, people go to familiar places where they’ll see their friends—which makes them less socially diverse. When relatively deprived areas become more socially diverse, however, it’s primarily because of people visiting those places. That kind of diversity, incidentally, is correlated with improvements on the deprivation index. In other words, gentrification doesn’t start when outsiders move in; it starts when outsiders come to visit.

The research is to be presented Wednesday at the 2016 International World Wide Web Conference in Montreal.

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