1. A computer-implemented method comprising: determining interests for each of a plurality of users of a social networking system, a respective interest for each user based on information provided by the respective user; inferring a preference of a user of the plurality of users for a first content item over a second content item, the inferring predicting, based on at least one of the determined interests for the user, which of the first and second content items the user would choose in a pair-wise comparison of the first and second content items; identifying at least one predictive factor associated with the inferred preference for the first content item over the second content item; for each identified predictive factor, determining a feedback coefficient for the identified predictive factor based on the inferred preference; and storing the feedback coefficients for the identified predictive factors in a computer-readable storage medium.