COLLABORATIVE FILTERING SYSTEM AND COLLABORATIVE FILTERING METHOD

When there are no evaluation values from a user who has evaluated broth contents X and Z, an indirect similarity calculation unit 32 of an arithmetic processing unit 30 of an information processing center 10a indirectly calculates the similarity between the contents X and Z using evaluation values of a content Y whose evaluation value is present from a user who has evaluated both the contents X and Y and whose evaluation value is present from a user who has evaluated both the contents Y and Z. A predicted evaluation value calculation unit 33 calculates a predicted evaluation value from a user who has not evaluated either of the contents X and Z using the similarity between the contents X and Z calculated by the indirect similarity calculation unit 32 and the evaluation values of the contents X and Z. Thus, it is possible to calculate the predicted evaluation values of the contents X and Z which are not directly calculable. Therefore, it becomes possible to further expand the range of contents whose evaluation values are predictable through collaborative filtering.