We consider an environment in which a principal hires an agent and evaluates his productivity over time in an ongoing relationship. The problem is embedded in a continuoustime model with both hidden action and hidden information, where the principal must induce the agent to exert effort to...

Despite widespread use in online transactions, rating systems only provide summary statistics of buyers' diverse opinions at best. To investigate the consequences of this coarse form of information aggregation, we consider a dynamic lemons market in which buyers share their evaluations...