16. The system of claim 13 , wherein determining the respective likeness scores of the particular users in relation to the first user, comprises: identifying one or more discriminating attributes; obtaining a weighted vector of attributes for the first user and for each of the particular users; adjusting a respective weight of the discriminating attributes in each of the vectors; and calculating the respective likeness score of each of the particular users as a difference between the weighted vector of attributes of the particular user and the weighted vector of attributes of the first user.
16. The system of claim 13 , wherein determining the respective likeness scores of the particular users in relation to the first user, comprises: identifying one or more discriminating attributes; obtaining a weighted vector of attributes for the first user and for each of the particular users; adjusting a respective weight of the discriminating attributes in each of the vectors; and calculating the respective likeness score of each of the particular users as a difference between the weighted vector of attributes of the particular user and the weighted vector of attributes of the first user. 18. The system of claim 16 , wherein identifying the discriminating attribute comprises clustering the plurality of users based on respective attributes of the users to identify the discriminating attributes that influence cluster membership.