Experimental Economics

, Volume 11, Issue 4, pp 390–401 | Cite as

Counterintuitive number effects in experimental oligopolies

  • Henrik OrzenEmail author


Recent theoretical research on oligopolistic competition suggests that under certain conditions prices increase with the number of competing firms. However, this counterintuitive result is based on comparative-static analyses which neglect the importance of dynamic strategies in naturally-occurring markets. When firms compete repeatedly, supra-competitive prices can become sustainable but this is arguably more difficult when more firms operate in the market. This paper reports the results of laboratory experiments investigating pricing behavior in a setting in which (static) theory predicts the counterintuitive number effect. Under a random matching protocol, which retains much of the one-shot nature of the model, the data corroborates the game-theoretic prediction. Under fixed matching duopolists post substantially higher prices, whereas prices in quadropolies remain very similar. As a result, the predicted effect is no longer observed, and towards the end the reverse effect is observed.


Market concentration Experiments Tacit collusion 


C72 C92 D43 


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Supplementary material


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Copyright information

© Economic Science Association 2007

Authors and Affiliations

  1. 1.School of EconomicsUniversity of NottinghamNottinghamUK

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