17. The system of claim 10 , where the quality score is based on the user receiving negative feedback from another user on an answer about the respective topic.
10. A system comprising: a processor; and computer-readable medium coupled to the processor and having instructions stored thereon, which, when executed by the 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.