Isle of Man City for Collusion is behavior that allows separate firms to approximate the behavior of a monopoly, thereby raising the profits of all firms within the industry. comparative advantage: the ability of one individual, firm, or nation to produce a specific good at lower opportunity cost than another individual, firm, or nation. complementary goods: goods related in consumption such that the two goods are purchased and consumed together (e.g., sugar and coffee). The demands for these goods are positively related, implying that increases in the demand for one good corresponds with increased demand for that good’s complements. concentration ratio: a measure calculated by summing up the squared market shares of all firms in a specific industry. Isle of Man City 2016.