We analyze data from experimental duopoly markets to assess the role information plays in facilitating collusion. In these markets, profitability can be common knowledge or private information. Market outputs are estimated in structures with symmetric and asymmetric costs under the two information conditions. Symmetric markets are more cooperative when profitability is common knowledge; asymmetric market outputs are unaffected by information differences. However, common knowledge in asymmetric markets increases the share of the output produced by the low-cost producer, and therefore increases industry efficiency.

Experimental duopolies are analyzed to answer two questions: Are asymmetric duopolies less likely to collude than symmetric duopolies? Is the time it takes to reach an equilibrium affected by asymmetry? In a repeated game where output is the choice, we have data 19 (respectively, 21) subject pairs where both agents are low-cost (respectively, high-cost) and 25 subject pairs where one agent in high-cost and one is low-cost. Subjects make choices for at least 35 periods. Results indicate that asymmetric markets are less cooperative and take longer to reach equilibrium than symmetric markets.

Richard Cornes, Charles F. Mason, Todd Sandler; The Commons and the Optimal Number of Firms*, The Quarterly Journal of Economics, Volume 101, Issue 3, 1 Au