微观经济学课件Ch_06

– 经济学家的职能之一就是使用他们的理论来协助制订 政策。
Price Control… 价格控制
• Are usually enacted when policymakers believe the market price is unfair to buyers or sellers.
– 当决策者认为市场价格对买者或卖者不公平时 通常会采用价格控制。
– 一个经济学家称房租控制是“摧毁一座城市最好的方法， 而不是轰炸。”
Rent Control in the Short Run... 短期内的租金控制
Rental Price of Apartment
Supply
Supply and demand for apartments are relatively inelastic 公寓的供给和需求相对 来说缺乏弹性
Two outcomes are possible when the government imposes a price ceiling: 当政府限定最高价格时，可能会有两种结果： • The price ceiling is not binding if set above the equilibrium price.
• Result in government-created price ceilings and floors.
– 由此产生了由政府创造的价格上限和下限。
Price Ceilings & Price Floors 价格上限和价格下限
Price Ceiling • A legally established maximum price at which a good can be sold.
Supply
…rent control causes a large shortage
Controlled rent
Shortage
Demand
0 Quantity of Apartments
纽约的故事
• 1943年，作为临时性战时措施之一，美国联邦政府实行了租 金控制。但是战争结束后，房租控制却被纽约州特别是纽约 市以法律的形式继承了下来。 • 在1975年，多达642000所公寓住房受到房租管制，另外有 650000所公寓住房受到一种被称为房租稳定化的复杂形式的 法规管辖。 • 1960年的普查显示：有25％的租房者支付了高于房租管制所 规定的法定房租的租金。应当注意这还不包括贿赂或质量下 降在内，这些只是人们支付超越指定价格的租金。 • 1970年，有33000个单元被遗弃，到1974年，又有10000多个 单元被遗弃。在布朗克斯区和曼哈顿岛东下端的一些地方， 整排被遗弃的公寓空无一人，被流浪者们穴居和拆散。 • 纽约市房租控制的长期性后果一直是住房存量的衰退和中低 收人的房客可获得的住房数量的下降，因为被豁免房租管制 而豪华公寓持续不断地被建造出来。
• nonprice rationing非价格配给
– Examples: Long lines, Discrimination by sellers – 例如：排长队，卖者歧视
Lines at the Gas Pump 加油站前的长队
In 1973 OPEC raised the price of crude oil in world markets. Because crude oil is the major input used to make gasoline, the higher oil prices reduced the supply of gasoline. 1973年，OPEC提高了世界市场上的原油价格，由于原 油是汽油的的主要原料，其价格上涨导致汽油供给的降 低。 What was responsible for the long gas lines?
• A price floor prevents supply and demand from moving toward the equilibrium price and quantity.
– 价格下限阻止攻击和需求向均衡的价格和数量移 动。
• When the market price hits the floor, it can fall no further, and the market price equals the floor price.
Controlled rent
Shortage
Demand
0 Quantity of Apartments
Rent Control in the Long Run 长期内的租来自百度文库控制
Rental Price of Apartment
Because the supply and demand for apartments are more elastic 长期内，公寓的供给和需求变 得富有弹性
加油站前的长队是谁造成的？
Economists blame government regulations that limited the price oil companies could charge for gasoline. 经济学家认为是政府管制造成的，管制限制了汽油的 价格。
The Price Ceiling on Gasoline Is Binding 当汽油的价格上限有约束作用时
Supply, Demand and Government Policies
• In a free, unregulated market system, market forces establish equilibrium prices and exchange quantities.
– 在一个自由的没有管制的市场体系中，市场力量自身 会达到均衡的价格和数量
– 价格上限是指法律规定的一个商品可以销售的最高价 格。
Price Floor • A legally established minimum price at which a good can be sold.
– 价格下限是指法律规定的一个商品可以销售的最低价 格。
Price Ceilings 价格上限
– 如果价格上限在均衡价格之上，则该最高限价没 有约束作用。
• The price ceiling is binding if set below the equilibrium price, leading to a shortage.
– 如果价格上限在均衡价格之下，则会导致短缺。
A Price Ceiling That Is Not Binding 价格上限没有约束作用
Price of Ice-Cream Cone
Supply
$4
Price ceiling
3
Equilibrium price
Demand
0 100 Equilibrium quantity Quantity of Ice-Cream Cones
A Price Ceiling That Is Binding 价格上限起约束作用
Price of Ice-Cream Cone Equilibrium price
Supply
$3
2
Price floor Demand
0
100
Equilibrium quantity
Quantity of Ice-Cream Cones
A Price Floor That Is Binding 有约束作用的价格下限
Price of Ice-Cream Cone
Supply Surplus
$4
$3
Equilibrium price
Price floor
Demand
0
80
Quantity demanded
120
Quantity supplied
Quantity of Ice-Cream Cones
Effects of a Price Floor 价格下限的结果
Price of Ice-Cream Cone
Supply
Equilibrium price $3 2 Price ceiling
Shortage
Demand
0 75 Quantity supplied 125 Quantity demanded Quantity of Ice-Cream Cones
• While equilibrium conditions may be efficient, it may be true that not everyone is satisfied.
– 即使均衡是有效率的，它也未必能使每个人都满意。
• One of the roles of economists is to use their theories to assist in the development of policies.
Price Floors价格下限
• When the government imposes a price floor, two outcomes are possible.
– 当政府实行价格下限时，可能会有两个结果：
• The price floor is not binding if set below the equilibrium price.
Effects of Price Ceilings 价格上限的结果
• A binding price ceiling creates ：
– 有约束的价格上限会导致：
• shortages because QD > QS.短缺
– Example: Gasoline shortage of the 1970s – 例如：1970年代的汽油短缺
Supply, Demand and Government Policies 供给、需求和政府政策
Chapter 6
Importance of Supply-Demand Analysis
A little knowledge goes a long way:
• Price Control, Taxation and other policies. – 价格管制、税收和其他政策 • Market welfare: Normative Analysis – 市场福利：规范分析 • International Trade – 国际贸易 • Externality (Market Failure) – 外部性（市场失灵） • Market Power (Market Failure) – 市场垄断（市场失灵） • Other markets: Financial Market, Labor Market. – 其它市场：金融市场，劳动市场 • Macroeconomics – 宏观经济学
– 如果价格下限设定在均衡价格之下，则它对市场没有 约束作用。
• The price floor is binding if set above the equilibrium price, leading to a surplus.
– 如果价格下限设定在均衡价格之上，则它会导致剩余 的产生。
A Price Floor That Is Not Binding 没有约束作用的最低限价
Price of Gasoline
S2
2. 如果供给下降
S1
P2
1. 价格上限
P1
4. 最终导致短缺
3. 价格上限约束
Demand
0
Q1
Quantity of Gasoline
Rent Control 房租限制
• Rent controls are ceilings placed on the rents that landlords may charge their tenants.
– 房租控制设定了房东在向租户收取租金时的最高额度。
• The goal of rent control policy is to help the poor by making housing more affordable.
– 房租控制的目标是帮助穷人，使得他们能够租得起房子。
• One economist called rent control “the best way to destroy a city, other than bombing.”