Abstract
This paper designs rating systems aimed at incentivizing users in UGC networks to produce content, thereby significantly improving the social welfare of such networks. We explicitly consider that monitoring user's production activities is imperfect. Such imperfect monitoring will lead to undesired rating drop of users, thereby reducing the social welfare of the network. The network topology constraint and users' heterogeneity further complicates the optimal rating system design problem since users' incentives are complexly coupled. This paper determines optimal recommendation strategies under a variety of monitoring scenarios. Our results suggest that, surprisingly, allowing a certain level of freeriding behavior may lead to higher social welfare than incentivizing all users to produce.