曼昆经济学原理(微观部分)垄断.ppt

内容提要 垄断企业（以及其他具有市场势力的企业）试图对有更高支付意愿的消费者收取更高的价格来增加利润，这种行为称为价格歧视； 政策制定者可以通过以下方法管制垄断：用反托拉斯法来赠强竞争，或者把垄断企业变为政府经营的企业。由于这些方法都存在问题，最好的选择可能是不作为。 * * Most students already know that monopoly means the firm is the only seller of its product. But the definition here has another very important part: In order for the firm to be considered a monopoly, the product it sells must have no close substitutes available from other firms. * * The horizontal axis of the graph measures number of homes provided electricity. The vertical axis measures the average total cost of providing electricity per home. * * A competitive firm is a price-taker, can sell as much as it wants at the market price. In effect, the competitive firm sells a product for which there are many perfect substitutes, so demand for its product is perfectly elastic; if it raises its price above the market price, demand for its product falls to zero. The relationship between P and MR is what distinguishes a competitive firm from a monopoly firm, in terms of both firm behavior and welfare implications. * * This slide introduces the notion that MR is not equal to P for the monopolist. The next slide presents an exercise to lead students to see for themselves what this relationship looks like. * * Note that a competitive firm has the output effect but not the price effect: the competitive firm does not need to reduce its price in order to sell a larger quantity, so, for the competitive firm, MR = P. * * It’s worth mentioning the following: Most people know that monopoly changes the way the economic “pie” is divided: by charging higher prices, the monopoly gets more surplus and consumers get less surplus. The analysis on this slide shows that the monopoly also reduces the size of the economic pie – by producing less than the socially efficient quantity and causing a deadweight loss. * * To keep the graph simple, this example assumes constant marginal cost. * * Here, there is no horizontal price