Can information imprecision be valuable? The case of credit ratings
研究了信用评级为何故意不精确（相对于违约概率），以及这种不精确性在什么情况下能提高社会福利，并讨论了监管干预的必要性。
We develop a model in which credit ratings are endogenously coarse relative to the underlying default probabilities, and ratings precision is countercyclical. Ratings coarseness arises from the profit-maximizing behavior of rating agencies, and coarseness may maximize welfare even when greater ratings precision is costlessly available. Because the private outcome may differ from the socially desirable outcome, a social planner can improve welfare by putting a ceiling (floor) on the rating agency’s fee if the desired outcome is coarseness (precision). Strikingly, when information production is costless, ratings coarseness is socially optimal, but it does not arise in the laissez-faire equilibrium, thus inviting regulatory intervention.