1. A method for selecting a subset of keywords from a set of master keywords in user profiles of social network users, comprising: computing a first histogram of each keyword in the master keywords based on the occurrence of the keywords in a first group of user profiles; computing a second histogram of each keyword in the master keywords based on the occurrence of the keywords in a second group of user profiles; computing a score based on a comparison of the first histogram and the second histogram for each keyword in the master keywords; ranking the master keywords based on the score of the keywords; and selecting a subset of keywords from the master keywords based on the ranking.