Should principals explain and justify their evaluations? Suppose the principal's evaluation is private information, but she can provide justication by sending a costly cheap-talk message. If she does not provide justication, her message space is restricted, but the message is costless. I show...

We consider a two-player contest model in which breakthroughs arrive according to privately observed Poisson processes. Each player’s process continues as long as she exerts costly effort. The player who collects the most breakthroughs until a predetermined deadline wins a prize.