... Types of economies of scale • Types of imperfect competition Oligopoly and monopoly Monopolistic competition • Monopolistic competition and trade • Inter-industry trade and intra-industry trade. .. size of the industry • Internal economies of scale occur when the cost per unit of output depends on the size of a firm Copyright © 20 06 Pearson Addison-Wesley All rights reserved 6- 5 Types of Economies. .. 20 06 Pearson Addison-Wesley All rights reserved 6- 23 Monopolistic Competition and Trade (cont.) Copyright © 20 06 Pearson Addison-Wesley All rights reserved 6- 24 Monopolistic Competition and Trade