A type of recommender system used by organizations to infer characteristics of individuals, usually with the aim of encouraging those individuals to make future purchases. For an individual (B, say), the aim is to use the apparent ratings of possible purchases that are made by individuals that the organization perceives as being similar to B, to predict the ratings that B would give: the top-rated predictions are then presented as suggestions to B. Internet shopping provides organizations with both rating evidence and the opportunity to present suggestions. Techniques used include correlation and the use of graphs.