1 1 第6章 Chapter 6 供给、需求与政府政策 Supply, Demand and Government Policies 2 供求分析的重要性 ?供求分析框架具有广泛而重要的运用。 A little knowledge goes a long way. ?价格控制、税收等政府（微观）政策 ?市场的福利特性：规范分析 ?国际贸易 ?外部性（市场不完美之一） ?垄断（市场不完美之二） ?扩展到各类市场：劳动市场、金融市场 ?扩展到宏观经济：一般均衡分析 3 供给、需求与政府政策 Supply, Demand, and Government Policies ?在自由的、无管制的市场中，市场的力量建立均衡价格， 决定交换的数量。 In a free, unregulated market system, market forces establish equilibrium prices and exchange quantities. ?虽然均衡的状态可能是有效率的，但也许并非使每人都满 意。 While equilibrium conditions may be efficient, it may be true that not everyone is satisfied. ?经济学家的作用之一是运用他们的理论帮助制定政府政策 One of the roles of economists is to use their theories to assist in the development of policies. 4 价格控制 Price Controls... ?实行价格控制通常是政府相信市场价格对 买方或卖方不公平。 Are usually enacted when policymakers believe the market price is unfair to buyers or sellers. ?两种价格控制：价格上限和价格下限 Result in government-created price ceilings and floors. 5 价格上限与价格下限 Price Ceilings & Price Floors 价格上限（Price Ceiling） ?法定最高价格。 A legally established maximum price at which a good can be sold. 价格下限（Price Floor） ?法定最低价格 A legally established minimum price at which a good can be sold. 6 价格控制在中国 ?经济适用房 ?粮食保护价、化肥限价 ?“看病难，看病贵” 2 7 价格上限 Price Ceilings 政府实行价格上限时有两种可能结果 Two outcomes are possible when the government imposes a price ceiling: ?当价格上限高于均衡价格时，价格上限没有限制性 The price ceiling is not binding if set above the equilibrium price. ?当价格上限低于均衡价格时，价格上限有限制性， 导致短缺。 The price ceiling is binding if set below the equilibrium price, leading to a shortage. 8 约束条件分类 Types of Constraints ?没有限制作用的约束条件（约束条件没有 限制性） A non-binding constraint (The constraint is not binding) ?有限制作用的约束条件（约束条件有限制 性） A binding constraint (The constraint is binding) 没有限制作用的价格上限 A Price Ceiling That Is Not Binding... $4 3 Quantity of Ice-Cream Cones 0 Price of Ice-Cream Cone 需求需求Demand 供给供给Supply 价格上限 Price ceiling 均衡价格 Equilibrium price 100 均衡数量 Equilibrium quantity 有限制作用的价格上限 A Price Ceiling That Is Binding... $3 Quantity of Ice-Cream Cones 0 Price of Ice-Cream Cone 2 Demand Supply 均衡价格均衡价格 Equilibrium price 价格上限价格上限 Price ceiling 短缺短缺 Shortage 125 Quantity demanded 75 Quantity supplied 供给量供给量 需求量需求量 11 实行价格上限的结果 Effects of Price Ceilings 有限制作用的价格上限导致短缺 A binding price ceiling creates shortages 因为需求量大于供给量 because Q D > Q S . 举例： ?70年代：食品 ?80年代：原材料（如钢铁） ?90年代：发售原始股 12 实行价格上限的结果 Effects of Price Ceilings 有限制作用的价格上限导致配给 A binding price ceiling creates rationing 因为有短缺Because of shortage 举例： ?排队queuing ?卖者对买者的歧视discrimination ?票证coupons ?审批examine and approve ?“走后门” going through a “back door” 3 13 谁应该对排长队负责？ 谁应该对走后门负责？ 经济学认为是政府的价格控制政策 Economists blame government price controls that limited the price the seller could charge. 既无效率，也未必公平 14 价格上限没有限制性 The Price Ceiling on Gasoline Is Not Binding $4 P 1 Quantity of Gasoline 0 Price of Gasoline Q 1 Demand Supply Price Ceiling 价格上限 1. Initially, the price ceiling is not binding... 开始时价格上 限没有限制性 15 价格上限变为有限制性 The Price Ceiling on Gasoline Is Binding P 1 Quantity of Gasoline 0 Price of Gasoline Q 1 需求Demand S 1 价格上限 Price ceiling S 2 2. 当供给减少 时…but when supply falls... P 2 3. 价格上限变为限 制性的…the price ceiling becomes binding... 4.导致短缺 …resulting in a shortage. 16 举例：房租控制Rent Control ?房租控制是指房主出租房屋时所收房租的上 限。 Rent controls are ceilings placed on the rents that landlords may charge their tenants. ?房租控制的目的是帮助穷人，使他们能负得 起房租。 The goal of rent control policy is to help the poor by making housing more affordable. ?一名经济学家称房租控制是“除了炸弹外摧毁 一座城市的最好的方法”。 One economist called rent control “the best way to destroy a city, other than bombing.” 17 房租控制在短期内的结果 Rent Control in the Short Run... 数量 Quantity of Apartments 0 房租 Rental Price of Apartment 需求Demand 供给Supply Controlled rent受控制的房租 短缺 Shortage 供给和需求较为 缺乏弹性 Supply and demand for apartments are relatively inelastic 18 房租控制在长期内的结果 Rent Control in the Long Run... Quantity of Apartments 0 Rental Price of Apartment Demand Supply 控制的房租Controlled rent 短缺 Shortage 因为供给和需求较为有 弹性 Because the supply and demand for apartments are more elastic... 房租控制导致严 重的短缺 rent control causes a large shortage 4 19 价格下限 Price Floors 政府实行价格下限时有两种可能结果。 When the government imposes a price floor, two outcomes are possible. ?当价格下限低于均衡价格时，价格下限没有限制性。 The price floor is not binding if set below the equilibrium price. ?当价格下限高于均衡价格时，价格下限有限制性，导致 过剩。 The price floor is binding if set above the equilibrium price, leading to a surplus. 20 没有限制作用的价格下限 A Price Floor That Is Not Binding... $3 Quantity of Ice-Cream Cones 0 Price of Ice-Cream Cone 100 Equilibrium quantity Equilibrium price Demand Supply 价格下 限 Price floor 2 有限制作用的价格下限 A Price Floor That Is Binding... $3 Quantity of Ice-Cream Cones 0 Price of Ice-Cream Cone Equilibrium price Demand Supply 价格下限 Price floor $4 120 Quantity supplied 80 Quantity demanded 过剩Surplus 22 实行价格下限的结果 Effects of a Price Floor ?价格下限阻止供给和需求向均衡价格 和数量移动。 A price floor prevents supply and demand from moving toward the equilibrium price and quantity. ?市场价格最多降到价格下限。 When the market price hits the floor, it can fall no further, and the market price equals the floor price. 23 实行价格下限的结果 Effects of a Price Floor 有限制作用的价格下限导致过剩，因为供给量大 于需求量。 A binding price floor causes a surplus because Q S >Q D . 非价格的配给机制：使用歧视性标准配给物品。 nonprice rationing is an alternative mechanism for rationing the good, using discrimination criteria. 例子：最低工资、农产品保护价格 Examples: The minimum wage, Agricultural price supports 24 最低工资 The Minimum Wage 价格下限的一个重要例子是最低工资 An important example of a price floor is the minimum wage. 最低工资法规定任何雇主必须支付受 雇者的最低价格 Minimum wage laws dictate the lowest price possible for labor that any employer may pay. 5 25 最低工资 The Minimum Wage 劳动量Quantity of Labor 0 工资Wage 均衡工资 Equilibrium wage 劳动需求Labor demand 劳动供给Labor supply 自由劳动市场 A Free Labor Market 均衡就业 Equilibrium employment 26 最低工资 Minimum wage 最低工资 The Minimum Wage Quantity of Labor 0 Wage Labor demand Labor supply 供给量 Quantity supplied 需求量 Quantity demanded 劳动过剩（失业） Labor surplus (unemployment) 有限制性最低工资的劳动市场 A Labor Market with a Minimum Wage 27 税收 Taxes 政府用征税方式来为公共项 目筹款。 Governments levy taxes to raise revenue for public projects. 28 税收 Taxes ?税收归宿（负担）研究谁承受税收负担 Tax incidence is the study of who bears the burden of a tax. ?税收改变市场均衡。 Taxes result in a change in market equilibrium. ?不管向谁征税，税收总使得买者付出更 多而卖者得到更少。 Buyers pay more and sellers receive less, regardless of whom the tax is levied on. 向买者征税的结果 Impact of a 50￠ Tax Levied on Buyers... 3.00 Quantity of Ice-Cream Cones 0 Price of Ice-Cream Cone 100 D 1 Supply, S 1 向买者征税使需求曲线 下移，幅度为税收量 A tax on buyers shifts the demand curve downward by the size of the tax ($0.50). D 2 3.00 Quantity of Ice-Cream Cones 0 Price of Ice-Cream Cone 10090 $3.30 买者支付的价格 Price buyers pay D 1 D 2 有税收时的均衡 Equilibrium with tax Supply, S 1 没有税收时的均衡 Equilibrium without tax 向买者征税的结果 Impact of a 50￠ Tax Levied on Buyers... 2.80 卖者得到的价格 Price sellers receive 无税收的 价格Price without tax Tax ($0.50) 6 31 税收的影响是什么？ What was the impact of tax? ?税收抑制市场活动。 Taxes discourage market activity. ?一个商品被征税，销售量 减小。 When a good is taxed, the quantity sold is smaller. ?买卖双方都承担税收负担 Buyers and sellers share the tax burden. 3.00 Quantity of Ice-Cream Cones 0 Price of Ice-Cream Cone 10090 S 1 S 2 Demand, D 1 向卖者征税的结果 Impact of a 50￠ Tax on Sellers... 没有税收 的价格 Price without tax 2.80 卖者得 到的价 格Price sellers receive $3.30 买者支付 的价格 Price buyers pay 没有税收时的均衡 Equilibrium without tax 向卖者征税使供给曲 线上移，幅度为税收 量A tax on sellers shifts the supply curve upward by the amount of the tax ($0.50). Tax ($0.50) 有税收时的均衡 Equilibrium with tax 33 比较向买者征税和向卖者征税的结果 Compare the effects of taxes on sellers with those on buyers? ?对买者征税和对卖者征税的均衡（最终） 结果是相同的！ ?买者和卖者分摊税收负担。 ?对买者征税和对卖者征税的唯一差别是谁 把钱交给政府。 34 税收负担 The Incidence of Tax ?税收负担在买者和卖者间是按何种比例划分 的？ In what proportions is the burden of the tax divided? 答案取决于答案取决于需求弹性需求弹性和和供给弹性供给弹性 The answers to these questions depend on the elasticity of demand and the elasticity of supply. 35 富有弹性的供给、缺乏弹性的需求 Elastic Supply, Inelastic Demand... 数量 Quantity 0 价格 Price 需求 Demand 供给 Supply 税收 Tax 1.当供给比需求更有弹性时 When supply is more elastic than demand 2. 税收负担更多 地由消费者承担 the incidence of the tax falls more heavily on consumers... 3. 更少地由 生产者承担 than on producers. 没有税收的价格 Price without tax 买者支付的价格 Price buyers pay 卖者得到的价格 Price sellers receive 36 缺乏弹性的供给、富有弹性的需求 Inelastic Supply, Elastic Demand... Quantity0 Price Demand Supply 没有税收的价格 Price without tax 税收 Tax 1.当需求比供给更有弹性时 When demand is more elastic than supply... 2.税收负担更多 地由生产者承担 the incidence of the tax falls more heavily on producers... 3.更少地由 消费者承担 than on consumers. 买者支付的价格 Price buyers pay 卖者得到的价格 Price sellers receive 7 37 税收负担是如何划分的？ So, how is the burden of the tax divided? 税收负担更多地落在市 场中缺乏弹性的一方 The burden of a tax falls more heavily on the side of the market that is less elastic. 38 为什么？ Why? 弹性是衡量当条件变得 不利时，买者或卖者离 开市场的意愿。 当征税时，不能轻而易 举离开市场的一方承担 更多的税收负担。 39 举例：工薪税与社会保障 Payroll Tax and Social Security 劳动量Quantity of Labor 0 工资Wage 没有税收的工 资Wage without tax Labor demand Labor supply 税收楔子 Tax wedge 企业支付的工 资Wage firms pay 工人得到的工资 Wage workers receive 40 举例：工薪税与社会保障 Payroll Tax and Social Security ?工薪税在雇员和企业之间的税收负担的 划分与法律规定的划分（比如平摊）无 关。 ?因为劳动的供给远比劳动的需求缺乏弹 性。 ?所以雇员而不是企业承担了大部分工薪 税的负担。 41 举例：谁支付奢侈品税？ Who Pays Taxes on Luxury Goods? ?对奢侈品征税似乎是向富人征税的有效 方式。 ?但是，因为对某一奢侈品的需求极富弹 性，但供应在短期内缺乏弹性。 ?所以，税收负担主要落在生产者（企业 和工人）身上。 ?事与愿违：奢侈品税的负担落在穷人身 上比富人身上要多。 42 总结 Summary ?价格控制包括价格上限和价格下限。 Price controls include price ceilings and price floors. ?价格上限是某种物品或服务价格的法定最高限。房租控 制是一例。 A price ceiling is a legal maximum on the price of a good or service. An example is rent control. ?价格下限是某种物品或服务价格的法定最低限。最低工 资是一例。 A price floor is a legal minimum on the price of a good or a service. An example is the minimum wage. 8 43 总结 Summary ?税收用来为公共目的筹集资金。 Taxes are used to raise revenue for public purposes. ?当政府对一种物品征税收时，该物品的均衡数量减 少。 When the government levies a tax on a good, the equilibrium quantity of the good falls. ?对一种物品征税是在买者支付的价格和卖者支付的 价格之间打入了一个楔子。 A tax on a good places a wedge between the price paid by buyers and the price received by sellers. 44 总结 Summary ?税收负担指的是谁承担税负。 The incidence of a tax refers to who bears the burden of a tax. ?税收负担不取决于是向买者征税，还是向卖者 征税。 The incidence of a tax does not depend on whether the tax is levied on buyers or sellers. ?税收负担取决于供给和需求的价格弹性。 The incidence of the tax depends on the price elasticities of supply and demand.