曼昆《经济学原理》6供给与需求：政府管制研究.ppt

6 Supply, Demand, and Government Policies Supply, Demand, and Government Policies In a free, unregulated market system, market forces establish equilibrium prices and exchange quantities. 在自由的、不存在规制的市场中，市场力量建立均衡价格和数量。 While equilibrium conditions may be efficient, it may be true that not everyone is satisfied. 均衡可能是有效率的，但并不是每个人对这种自由市场调整的结果都感到满意。 One of the roles of economists is to use their theories to assist in the development of policies. 经济学家的一个职责就是运用理论帮助政府制定政策。 CONTROLS ON PRICES 价格控制 Are usually enacted when policymakers believe the market price is unfair to buyers or sellers. Result in government-created price ceilings and price floors. 当政策制定者认为，对卖者或者买者而言，价格不公时，会采取控制价格的措施。比如，价格上限、价格下限。 CONTROLS ON PRICES Price Ceiling 价格上限 A legal maximum on the price at which a good can be sold. 法定最高价格 Price Floor 价格下限 A legal minimum on the price at which a good can be sold. 法定最低价格 How Price Ceilings Affect Market Outcomes价格上限如何影响市场结果 Two outcomes are possible when the government imposes a price ceiling: 政府制定价格上限会有两种可能的结果： The price ceiling is not binding if set above the equilibrium price. 如果制定的价格高于均衡价格，那么价格上限没有限制作用。 The price ceiling is binding if set below the equilibrium price, leading to a shortage. 如果制定的价格上限低于均衡价格，那么价格价格上限有限制作用，会导致短缺。 Figure 1 A Market with a Price Ceiling Figure 1 A Market with a Price Ceiling How Price Ceilings Affect Market Outcomes价格上限如何影响市场结果 Effects of Price Ceilings：价格上限的作用 A binding price ceiling creates Shortages because QD QS. 短缺 Example: Gasoline shortage of the 1970s Non price rationing 非价格配给 Examples: Long lines, discrimination by seller 当政府对竞争市场实行限制性价格上限时，会产生物品的短缺，卖者在大量的买者中配给稀缺物品。这种配给制很少是合意的。排长队无效率，根据卖者偏好的歧视既无效率，也不公平。 CASE STUDY: Lines at the Gas Pump In 1973, OPEC raised the price of crude oil in world markets. Crude oil is the major input in gasoline, so the higher oil prices reduced the supply of gasoline. What was responsible for the long gas lines? 经典案例：加油站前排长队 1973年石油输出国组织提高原油价格，原油是生产汽油的主要投入，结果导致生产汽油的成本上升，汽油供给减