The Econometrics of Cartel Overcharges

By Marcel Boyer and Rachidi Kotchoni

Connor and Lande (2006) conducted a survey of cartel overcharge estimates and found an average in the range of 31% to 49%. By examining more sources, Connor (2010b) finds a median of 23.3% for all type of cartels and a mean of 50.4% for successful cartels. However, the data used in these studies are estimates rather than true observations, since the true illegal profits of cartels are rarely observable. Therefore, these data are subject to model error, estimation error and publication bias. A quick glance at the Connor database reveals that the universe of overcharge estimates is asymmetric, heterogenous and contains a number of influential observations. Beside the fact that overcharge estimates are potentially biased, fitting a linear OLS model to the data without providing a careful treatment of the problems raised by the publication bias, outliers, asymmetry, and heterogeneity will necessarily produce distorted results. We conduct a meta-analysis of cartel overcharge estimates in the spirit of Connor and Bolotova (2006), but providing a sound treatment of the matters raised above. We find for cartels with initial overcharge estimates lying between 0% and 50%.a bias-corrected mean overcharge estimate of 13.6% with a median of 13.6% and for all cartels of all types a bias-corrected mean of 17.5% with a median of 14.1%

Paris: Institut de Polytechnic Paris, Département d'Économie de l'École Polytechnique, 2011. 60p.