Geography
and social relationships are inextricably
intertwined. As people spend more time online,
data regarding these two dimensions are becoming
increasingly precise, allowing building reliable
models to describe their interaction. In
[11], the study of user-contributed address and
association data from Facebook shows that the
addition of social information produces
improvement in accuracy of predicting physical
location. First, friendship as a function of distance
and rank is analyzed. It is found that at
medium to long-range distances, the probability
of friendship is roughly proportional to the
inverse of distance. However, at shorter ranges,
distance does not influence much. Then the
maximum likelihood approach is presented to
predict the physical location of a user, given the
known location of her friends. This method predicts
the physical location of 69.1 percent of the
users with 16 or more located friends to within
25 mi, compared to only 57.2 percent using IPbased
methods.