An Active Approach to Collaborative Filtering

Collaborative filtering allows the preferences of multiple users to be pooled in a principled way in order to make recommendations about products, services or information unseen by a specific user. We consider here the problem of online and interactive collaborative filtering: given the current ratings and recommendations associated with a user, what queries (new ratings) would most improve the quality of the recommendations made? This can be cast in a straightforward fashion in terms of expected value of information; but the online computational cost of computing optimal queries is prohibitive. We show how offline precomputation of bounds on value of information, and of prototypes in query space, can be used to dramatically reduce the required online computation. The framework we develop is quite general, but we derive detailed bounds for the multiplecause vector quantization model, and empirically demonstrate the value of our active approach using this model.