Internal migration and mobile communication patterns among pairs with strong ties.

Using large-scale call detail records of anonymised mobile phone service subscribers with demographic and location information, we investigate how a long-distance residential move within the country affects the mobile communication patterns between an ego who moved and a frequently called alter who did not move. By using clustering methods in analysing the call frequency time series, we find that such ego-alter pairs are grouped into two clusters, those with the call frequency increasing and those with the call frequency decreasing after the move of the ego. This indicates that such residential moves are correlated with a change in the communication pattern soon after moving. We find that the pre-move calling behaviour is a relevant predictor for the post-move calling behaviour. While demographic and location information can help in predicting whether the call frequency will rise or decay, they are not relevant in predicting the actual call frequency volume. We also note that at four months after the move, most of these close pairs maintain contact, even if the call frequency is decreased.