1. A computer-implemented method comprising: receiving, at a social networking system from a user via a client device, metadata associated with a target object maintained by the social networking system; determining an amount of metadata previously received from the user and associated with one or more stored objects maintained by the social networking system; retrieving characteristics of the user derived from information stored by the social networking system if the amount of metadata previously received from the user is less than a threshold amount of metadata; identifying additional users of the social networking system having respective confidence values of at least a threshold confidence value, wherein the respective confidence values represent measures of accuracy of metadata provided by the respective additional users in association with the one or more objects maintained by the social networking system; comparing the characteristics of the user to characteristics of the identified additional users; calculating a confidence value associated with the user based on a similarity between the characteristics of the user and the characteristics of the identified additional users; and storing the metadata in association with the object if the confidence value associated with the user exceeds the threshold confidence value.