19. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by a processor, cause the processor to perform operations comprising: determining, for each of one or more topics associated with the user, an expertise score indicating a level of expertise the user has with the respective topic, a responsiveness score indicating responsiveness of the user to previous questions routed to the user about the respective topic, and a quality score indicating a quality of answers, by the user, to the previous questions about the respective topic; obtaining one or more additional topics, not explicitly associated with the user; determining, for each of one or more additional topics, an expertise score indicating a level of expertise the user has with the respective additional topic; associating for each of the one or more topics and the one or more additional topics, the expertise score, the responsiveness score, and the quality score with the user; and selectively routing one or more queries to the user in response to the user being identified as a candidate answerer from a plurality of users based on one or more of the expertise score, the responsiveness score and the quality score.
19. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by a processor, cause the processor to perform operations comprising: determining, for each of one or more topics associated with the user, an expertise score indicating a level of expertise the user has with the respective topic, a responsiveness score indicating responsiveness of the user to previous questions routed to the user about the respective topic, and a quality score indicating a quality of answers, by the user, to the previous questions about the respective topic; obtaining one or more additional topics, not explicitly associated with the user; determining, for each of one or more additional topics, an expertise score indicating a level of expertise the user has with the respective additional topic; associating for each of the one or more topics and the one or more additional topics, the expertise score, the responsiveness score, and the quality score with the user; and selectively routing one or more queries to the user in response to the user being identified as a candidate answerer from a plurality of users based on one or more of the expertise score, the responsiveness score and the quality score. 21. The computer-readable medium of claim 19 , further comprising associating one or more of the topics with each member in the social affinity group.