Similar definition has been shown effective in characterizing social distance in social networks extracted from communication data (Lin et al., 2012;Wen and Lin, 2010).
it is dist(i, j) = , where v 1 , ..., v k are the nodes on the shortest path from user i to user j, and strength(v k , v k+1 ) measures the strength of interactions between v k and v k+1 as: , where X ij is the total interactions between user i and j, including both retweeting and mentioning (If X ij < 10, we set strength(i, j) = 0).