User talk:Kefei Yin/sandbox

product groups
Product groups refers to under the condition of monopolistic competition, because the basic performance of the products of each manufacturer is the same but there are differences between the products, and those products have the same basic performance, but there are differences in the products, and there is a close substitution relationship between the products. They will choose to join together to form a group. Under perfect competition, all firms producing homogeneous products constitute an industry because the products are homogeneous. Under complete monopoly conditions, one firm represents one industry. There are a large number of manufacturers in the same product group, and each manufacturer is small in absolute scale or relative scale. The products of each manufacturer account for a very small proportion of the entire market, and individual manufacturers are unable to influence the market of the entire product group. In addition, because there are so many manufacturers in the same product group, each manufacturer expects that its actions will not be noticed by its opponents, so the actions it takes will not cause its opponents to retaliate.