You can predict city gentrification through check-ins and tweets

Engadget 

Moreover, the very people who tend to use Foursquare and Twitter work to the advantage of this predictive model. The researchers believe that the people who most often use these networks tend to be the affluent types who create gentrification. The very fact that they're showing up in a given region, however temporarily, may be proof enough that demographics are changing. There's only been a limited amount of testing so far, but it's promising. The check-ins and tweets accurately predicted the gentrification of London's Hackney area in recent years, and they've already identified a few additional areas (Greenwich, Hammersmith, Lambeth and Tower Hamlets) that could be next.