经济学原理(4.20) 的.ppt

第四章 厂商理论扩展 提出问题： 厂商如何制定价格策略？ Suppose that the monopolist seeks to maximize its economic profit, What output level y* maximizes profit? The tax increases marginal cost to $(k+t)/output unit, changing the profit-maximizing price to The amount of the tax paid by buyers is 一级价格歧视使用的条件 一级价格歧视的例子 一级价格歧视的效率分析 二级价格歧视使用的条件 二级价格歧视使用的原因 Two consumers Person A has low willingness-to-pay Person B has high willingness-to-pay 2nd-degree discrimination can also occur in the dimension of quality Eg. Different prices for different seats in a theater Eg. Different prices for economy class vs. business class seats in airplanes A two-part tariff is a lump-sum fee, p1, plus a price p2 for each unit of product purchased. Thus the cost of buying x units of product is p1 + p2x. 先征收固定费用，再根据消费量按照固定的单价收费。 p = p1 + p2x. 垄断厂商采用两步定价法时，为了获取最大利润，通常将P2定在等于边际成本的水平，而P1等于此时的消费者剩余。两步定价法同样可以达到最有效率的状态。 垄断竞争 1、含义： 很少有厂商能够真正垄断市场，这是因为，在不存在进入门槛的情况下，竞争对手虽然不能生产与之完全一样的产品，但可以生产与之相似的替代品。我们将这种现象称为垄断竞争。 2、垄断厂商所面临的变化 2、垄断厂商所面临的变化 需求曲线向内移动 2、垄断厂商所面临的变化 需求曲线向内移动 需求曲线变得比过去更加平坦，更有弹性 垄断利润消失 2、垄断厂商所面临的变化 需求曲线向内移动 需求曲线变得比过去更加平坦，更有弹性 垄断利润消失 2、垄断厂商所面临的变化 需求曲线向内移动 需求曲线变得比过去更加平坦，更有弹性 垄断利润消失 Suppose firm 1 takes firm 2’s output level choice y2 as given. Then firm 1 sees its profit function as An equilibrium is when each firm’s output level is a best response to the other firm’s output level, for then neither wants to deviate from its output level. A pair of output levels (y1*,y2*) is a Cournot-Nash equilibrium if An Example Suppose that the market inverse demand function is and that the firms’ total cost functions are An Example Suppose that the market inverse demand function is and that the firms’ total cost functions are 分析工具：等利润线（ Iso-Profit Curves） 分析工具：等利润线（ Iso-Profit Curves） For firm 1, an iso-profit curve contains all the output pairs (y1,y2) giving firm 1 the same profit level P1 （1）厂商为什么会共谋？ So there are profit incentives for both firms to “cooperate” by lowering their output l