Abstract: Predictions are based primarily upon similarities in pairs of ratings, irrespective of the actual value of the ratings. A table is used to translate each pair of ratings into rankings that are used to make predictions of future ratings. Similar ratings are ranked higher than dissimilar ratings. The prediction is based upon the average () of the books linked to the book of interest, as rated by the user, plus the difference (&dgr;) between the average rating of the book of interest, as rated by all users, and the average ratings of the linked books, as rated by the user. The averages may be weighted by the rankings. Alternatively, the prediction is based upon the cumulative values applied to books linked to the books rated by the user, where the values are based upon the user's ratings of the rated books.