It is well known that the presence of imperfect monitoring limits the possibility of making efficient agreements. When firms interact repeatedly in multiple markets, however, we show that noisy observations may improve the possibility of collusion. When observation is noisy in at least one...

Successful upstream collusion must satisfy both the incentive constraint (keeping cartel members in line) and the compensation constraint (preventing lawsuits from downstream firms). Our analysis shows that there is a non-monotonic and inverted U-shaped relationship between cartel incidence and...