Estimation The Monopoly Welfare Loss in for Selective Industries in Iran: A Comparison Between New Theoretical Oligopoly Approaches and the Traditional SCP Models

The question mentioned in the current paper addresses whether the different methods of estimating welfare loss propose the same ranking of different industries based on deadweight loss and their degreeof monopoly. Answering this question is very valuable from the view of the antitrust policies compilation in different industries.Hence, in order to answer the mentioned question, deadweight losses in Iran’sten selected industrieshave been estimated, based on three different theoretical approaches (Structure- Conduct- Performance, Price leadership and industry-wide oligopoly pricing models),over the period 1995 to 2007. The results demonstrate that the ranking of industries according to theirdegree of monopoly, type of theoretical approach and the indicators which are used forcalculating the deadweight losses, are different. Therefore, precautions should be taken in targeting industries for antitrust policy- making. In fact, relyingsolelyon the results of a model, regardless of the structure of the industry, the performance of firms and the adaptation of the model to the conditions of the industries, can be misleading.