Encyclopedia of Economics 3 1 2020 03 20 Concentration Indices in Industry Concentration Indices in Industry 1 3 4484 FA Nader Mehregan Department of Economics, Bu-Ali Sina University, Hamedan, Iran. Younes Teimori mporg.ir Journal Article 2019 10 07 Industrial concentration is one of the most important concepts and characteristics of market structure that determines nature and extent of competition in an industry. If the issue of how is distribution of market power across geographic areas is concerned, problem of geographic concentration will be raised. But Also, If the issue of how is distribution of market power among firms in an industry is concerned, the problem of market concentration is raised. Here, selective of the indicators of market and geographic concentration measurement are presented: Herfindhal- Hirshman Market Concentration Index (H), Rothschild concentration index (R), Ellison- Glaeser Geographic Concentration Index (EG) and Iso - Concentration Curves (ICC). Industrial concentration is one of the most important concepts and characteristics of market structure that determines nature and extent of competition in an industry. If the issue of how is distribution of market power across geographic areas is concerned, problem of geographic concentration will be raised. But Also, If the issue of how is distribution of market power among firms in an industry is concerned, the problem of market concentration is raised. Here, selective of the indicators of market and geographic concentration measurement are presented: Herfindhal- Hirshman Market Concentration Index (H), Rothschild concentration index (R), Ellison- Glaeser Geographic Concentration Index (EG) and Iso - Concentration Curves (ICC). http://enceco.ihcs.ac.ir/article_4484_ddd5eab5aaeca0a92d6a325d40c5a440.pdf