Collusion with secret price cuts: an experimental investigation

Theoretical work starting with Stigler (1964) suggests that collusion may be difficult to sustain in a repeated game with secret price cuts and demand uncertainty. Compared to equilibria in games of perfect information, trigger-strategy equilibria in this context result in lower payoffs because punishments occur along the equilibrium path. We tested the theory in a series of economic experiments. Consistent with the theory, treatments with imperfect information were less collusive than treatments with perfect information. However, in the imperfect-information treatments, players seemed to settle on the static Nash outcome rather than using trigger strategies. Players did resort to punishments for undercutting in perfect-information treatments, and this sometimes led to successful collusion afterward.