The Relative Effi cacy of Price Announcements and Express Communication for Collusion: Experimental Findings∗

Collusion is when firms coordinate on suppressing competition, and coordination typically requires that firms communicate in some manner. This study conducts experiments to determine what modes of communication are able to produce and sustain collusion and how the effi cacy of communication depends on firm heterogeneity and the number of firms. We consider two different communication treatments: non-binding price announcements and unrestricted written communication. Our main findings are that price announcements allow subjects to coordinate on a high price but only under duopoly and when firms are symmetric. While price announcements do result in higher prices when subjects are asymmetric, there is little evidence that they are coordinating their behavior. When subjects are allowed to engage in unrestricted communication, coordination on high prices occurs whether they are symmetric or asymmetric. We find that the incremental value to express communication (compared to price announcements) is greater when firms are asymmetric and there are more firms.