We compare evaluations of employee performance by individuals and groups of supervisors, analyzing a formal model and running a laboratory experiment. The model predicts that multi-rater evaluations are more precise than single-rater evaluations if groups rationally aggregate their signals about...

Both institutional and individual investors have a vast array of advisory and ratings services to assist with security selection. One of the most prominent sources of stock ratings is Morningstar. This is the first large-scale study evaluating the performance of portfolios formed using...