I haven’t read this working paper yet – just struck by this dataset:
“We leverage a rich new source of ‘digital trace’ data to provide a detailed empirical perspective on how social networks influence the decision to migrate. These data capture the entire universe of mobile phone activity in Rwanda over a five-year period. Each of roughly one million individuals is uniquely identified throughout the dataset, and every time they make or receive a phone call, we observe their approximate location, as well as the identity of the person they are talking to. From these data, we can reconstruct each subscriber’s 5-year migration trajectory, as well as a detailed picture of their social network before and after migration