Predictive accuracy is not enough

Sun Labs researcher Paul Lamere posts a list of properties of a good music recommender system:

A good recommendation has three aspects:

familiarity - to help us gain trust in the recommender
novelty - without new music, the recommendation is pointless
relevance - the recommended music has to match my taste

The emphasis on credibility is insightful. Recommendations that are too obscure may be perceived as low quality because the user cannot easily and quickly evaluate them.

This is just one of many examples of the yawning gap between predictive accuracy -- accurately predicting what people want to buy next -- and perceived quality -- the usefulness of the recommendations to users.