Supply, Demand and Government Policies
供给、需求与政府政策
Chapter 6
Controls on Price... 价格控制…
Are usually enacted when policymakers believe the market price is unfair to buyers or sellers.
当政策制定者认为市场价格对买者或卖者不公平时，往往实行价格控制。
Result in government-created price ceilings and floors.
这就促使政府实行价格上限和价格下限政策。
Controls on Price... 价格控制…
Price Ceiling 价格上限
A legally established maximum price at which a good can be sold.
可以出售一种物品的法定最高价格。
Price Floor 价格下限
A legally established minimum price at which a good can be sold.
可以出售一种物品的法定最低价格。
A Price Ceiling That Is Not Binding...
$4
3
Quantity of
Ice-Cream
Cones
0
Price of
Ice-Cream
Cone
Demand
Supply
Price
ceiling
Equilibrium
price
100
Equilibrium
quantity
没有限制作用的价格上限...
$4
3
冰激凌蛋卷的数量
0
冰激凌蛋卷
的价格
需求
供给
价格上限
均衡价格
100
均衡数量
A Price Ceiling That Is Binding...
$3
Quantity of
Ice-Cream
Cones
0
Price of
Ice-Cream
Cone
2
Demand
Supply
Equilibrium
price
Price
ceiling
Shortage
125
Quantity
demanded
75
Quantity
supplied
有限制作用的价格上限...
$3
冰激凌蛋卷的数量
0
冰激凌蛋卷
的价格
2
需求
供给
均衡价格
价格上限
短缺
125
需求量
75
供給量
How Price Ceilings Affect Market Outcomes
Effects of Price Ceilings
A binding price ceiling creates ...
shortages because QD > QS.
Example: Gasoline shortage of the 1970s
nonprice rationing
Examples: Long lines, Discrimination by sellers
价格上限如何影响市场结果
价格上限的作用
有限制作用的价格上限造成...
短缺，因为 QD > QS.
例子: 70年代的汽油短缺
非市场价格方式配给
例子: 排长队, 卖者歧视
Lines at the Gas Pump
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.
What was responsible for the long gas lines?
Economists blame government regulations that limited the price oil companies could charge for gasoline.
加油站前的长队
1973年，石油输出国组织（ OPEC)提高了世界石油市场的原油价格。由于原油是用于生产汽油的主要投入，较高石油价格减少了汽油供给。
谁对加油站前的长队负责？
经济学家把它归咎于限制石油公司对汽油可以收取的价格的政府管制。
The Price Ceiling on Gasoline Is Not Binding...
汽油的价格上限没有限制性…
$4
P1
Quantity of Gasoline
汽油数量
0
Price of Gasoline
汽油价格
Q1
Demand 需求
Supply 供给
Price ceiling
价格上限
1. Initially, the
price ceiling is not binding...
1.原来，价格上限没有限制性…
The Price Ceiling on Gasoline Is Binding...
P1
Quantity of
Gasoline
0
Price of
Gasoline
Q1
Demand
S1
Price
ceiling
S2
2. …but when supply falls...
P2
3. …the price ceiling becomes binding...
4. …resulting in a shortage.
汽油的价格上限有限制性...
P1
汽油数量
0
汽油价格
Q1
需求
S1
价格上限
S2
2. …但当供给减少时...
P2
3. …价格上限变为限制性的...
4. …导致短缺。
Rent Control in the Short Run and Long Run
Rent controls are ceilings placed on the rents that landlords may charge their tenants.
The goal of rent control policy is to help the poor by making housing more affordable.
One economist called rent control “the best way to destroy a city, other than bombing.”
短期中和长期中的租金控制
租金控制——房东能向房客收取的租金上限。
这一政策的目的是帮助穷人更能租得起住房。
一位经济学家称租金控制是“除了轰炸之外毁灭一个城市的最好方法”。
Rent Control in the Short Run...
Quantity of
Apartments
0
Rental Price of
Apartment
Demand
Supply
Controlled rent
Shortage
Supply and demand for apartments are relatively inelastic
短期的租金控制...
公寓数量
0
公寓租金
价格
需求
供给
受控制的租金
短缺
供给与需求都相对缺乏弹性
Rent Control in the Long Run...
Quantity of
Apartments
0
Rental Price of
Apartment
Demand
Supply
Controlled rent
Shortage
Because the supply and demand for apartments are more elastic...
…rent control causes a large shortage
长期的租金控制...
公寓数量
0
公寓租金
价格
需求
供给
受控制的租金
短缺
因为供给和需求更富有弹性…
…租金控制导致大量短缺
How Price Floors Affect Market Outcomes
When the government imposes a price floor, two outcomes are possible.
The price floor is not binding if set below the equilibrium price.
The price floor is binding if set above the equilibrium price, leading to a surplus.
价格下限如何影响市场结果
当政府实行价格下限时，可能出现两种价格：
如果价格下限低于均衡价格，价格下限没有限制作用。
如果价格下限高于均衡价格，价格下限对市场有限制作用，导致过剩。
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
Price
floor
2
没有限制性的价格下限...
$3
冰激凌蛋卷的数量
0
冰激凌蛋卷
的价格
100
均衡数量
均衡价格
需求
供给
价格下限
2
A Price Floor That Is Binding...
$3
Quantity of
Ice-Cream
Cones
0
Price of
Ice-Cream
Cone
Equilibrium
price
Demand
Supply
Price floor
$4
120
Quantity
supplied
80
Quantity
demanded
Surplus
有限制性的价格下限...
$3
冰激凌蛋卷的数量
0
冰激凌蛋卷
的价格
均衡价格
需求
供给
价格下限
$4
120
供給量
80
需求量
过剩
How Price Floors Affect Market Outcomes
价格下限如何影响市场结果
A price floor prevents supply and demand from moving toward the equilibrium price and quantity.
价格下限阻止供给和需求调整到均衡价格和均衡数量
When the market price hits the floor, it can fall no further, and the market price equals the floor price.
当市场价格达到下限时，它就不能再下降，此时市场价格等于下限价格。
The Minimum Wage 最低工资
An important example of a price floor is the minimum wage. Minimum wage laws dictate the lowest price possible for labor that any employer may pay.
价格下限的一个重要例子是最低
工资。最低工资法规定了任何一
个雇主要支付的最低劳动工资价格
The Minimum Wage 最低工资
Quantity of Labor
劳动量
0
Wage
工资
Equilibrium
Wage
均衡工资
Labor demand
劳动需求
Labor supply
劳动供给
A Free Labor Market
自由市场
Equilibrium
Employment均衡就业
How the Minimum Wage Affects the Labor Market
Minimum
wage
Quantity of
Labor
0
Wage
Labor
demand
Labor
supply
Quantity
supplied
Quantity
demanded
Labor surplus
(unemployment)
A Labor Market with a Minimum Wage
最低工资如何影响劳动市场
最低工资
劳动量
0
工资
劳动需求
劳动供给
供給量
需求量
劳动过剩
(失业)
有限制性最低工资的劳动市场
Taxes 税收
Governments levy taxes to raise revenue for public projects.
政府利用税收为公共项目筹资
How Taxes on Buyers (and Sellers) Affect Market Outcomes
Taxes discourage market activity.
When a good is taxed, the quantity sold is smaller.
Buyers and sellers share the tax burden.
对买者和卖者收税如何影响市场结果
税收抑制了市场活动。
当一种物品被征税时，它的销售量减少。
买者和卖者分摊税收负担。
Elasticity and Tax Incidence
Tax incidence is the study of who bears the burden of a tax.
Taxes result in a change in market equilibrium.
Buyers pay more and sellers receive less, regardless of whom the tax is levied on.
弹性与税收归宿
税收归宿 ——关于由谁承担税收负担的研究。
税收导致市场均衡的变动。
不管向谁收税，买者支付的价格更高，卖者收到的价格更低。
Impact of a 50¢ Tax Levied on Buyers...
Quantity of
Ice-Cream Cones
0
Price of
Ice-Cream
Cone
100
D1
Supply, S1
A tax on buyers
shifts the demand
curve downward
by the size of
the tax ($).
D2
向买者征收美元税收的影响…
冰激凌蛋卷的数量
0
冰激凌蛋卷
的价格
100
D1
供给, S1
对买者征税使需求
曲线下移，其幅度
为税收量（美元）
D2
Impact of a 50¢ Tax Levied on Buyers...
Quantity of
Ice-Cream Cones
0
Price of
Ice-Cream
Cone
100
90
$
Price
buyers
pay
D1
D2
Equilibrium
with tax
Supply, S1
Equilibrium without tax
Price
sellers
receive
Price
without
tax
Tax ($)
向买者征收美元税收的影响…
冰激凌蛋卷的数量
0
冰激凌蛋卷
的价格
100
90
$
买者支付
的价格
D1
D2
有税收时
的均衡
供给, S1
没有税收时的均衡
卖者得到
的价格
没有税收
时的价格
税收 美元
Impact of a 50¢ Tax on Sellers...
Quantity of
Ice-Cream Cones
0
Price of
Ice-Cream
Cone
100
90
S1
S2
Demand, D1
Price without tax
Price sellers receive
$
Price buyers pay
Equilibrium without tax
A tax on sellers shifts the supply curve upward by the amount of the tax ($).
Tax ($)
Equilibrium
with tax
向卖者征收美元税收的影响…
冰激凌蛋卷的数量
0
冰激凌蛋卷
的价格
100
90
S1
S2
需求, D1
没有税收
时的价格
卖者得到的价格
$
买者支付
的价格
没有税收时的均衡
向卖者征税使供给曲线向上移动，移动量为税收（美元）
税收 美元
有税收时
的均衡
A Payroll Tax
Quantity of
Labor
0
Wage
Wage without tax
Labor
demand
Labor
supply
Tax wedge
Wage firms pay
Wage workers receive
工薪税
劳动量
0
工资
没有税收
时的工资
劳动需求
劳动供给
税收楔子
企业支付
的工资
个人得到
的工资
Elasticity and Tax Incidence
In what proportions is the burden of the tax divided?
How do the effects of taxes on sellers compare to those levied on buyers?
The answers to these questions depend on the elasticity of demand and the elasticity of supply.
弹性与税收归宿
税收负担是按什么比例分摊的？
怎样比较向买者征税与向卖者征税的结果？
这些问题的答案取决于需求弹性 和供给弹性 。
（a）Elastic Supply, Inelastic Demand...
Quantity
0
Price
Demand
Supply
Tax
1. When supply is more
elastic than demand...
2. ...the
incidence of the
tax falls more
heavily on
consumers...
3. ...than on
producers.
Price without tax
Price buyers pay
Price sellers receive
Figure 9 How the Burden of a Tax Is Divided
（a）供给富有弹性，需求缺乏弹性...
数量
0
价格
需求
供给
税收
当供给比需求富
有弹性时...
2. …税收归宿
更多地由消费
者承担...
3. …更少地由
生产者承担。
没有税收的价格
买者支付的价格
卖者得到的价格
图9. 税收负担如何分摊的
(b)Inelastic Supply, Elastic Demand...
Quantity
0
Price
Demand
Supply
Price without tax
Tax
1. When demand is more
elastic than supply...
2. ...the
incidence of
the tax falls more
heavily on producers...
3. ...than on consumers.
Price buyers pay
Price sellers receive
Figure 9 How the Burden of a Tax Is Divided
(b)供给缺乏弹性，需求富有弹性...
数量
0
价格
需求
供给
没有税收的价格
税收
1. 当需求比供给富有弹性时...
2. …税收归宿更多
地由生产者承担...
3. …更少地由消费者承担
买者支付的价格
卖者得到的价格
图9. 税收负担如何分摊的
So, how is the burden of the tax divided?
The burden of a tax falls more heavily on the side of the market that is less elastic.
ELASTICITY AND TAX INCIDENCE
所以, 税收负担是如何分摊的?
税收负担更多地落在缺乏弹性的市场一方身上。
弹性与税收归宿
Summary
Price controls include price ceilings and price floors.
A price ceiling is a legal maximum on the price of a good or service. An example is rent control.
A price floor is a legal minimum on the price of a good or a service. An example is the minimum wage.
小结
价格控制包括价格上限和价格下限。
价格上限是某种物品或劳务价格法定的最高限。租金控制是一个例子。
价格下限是某种物品或劳务价格法定的最低限。最低工资是一个例子。
Summary
Taxes are used to raise revenue for public purposes.
When the government levies a tax on a good, the equilibrium quantity of the good falls.
A tax on a good places a wedge between the price paid by buyers and the price received by sellers.
小结
税收是用来为公共目的筹资的。
当政府对一种物品征税时，该物品的均衡数量减少。
对一种物品征税是在买者支付的价格与卖者得到的价格之间打入了一个楔子。
Summary
The incidence of a tax refers to who bears the burden of a tax.
The incidence of a tax does not depend on whether the tax is levied on buyers or sellers.
The incidence of the tax depends on the price elasticities of supply and demand.
The burden tends to fall on the side of the market that is less elastic.
小结
税收归宿是指谁承担了税收负担。
税收归宿不取决于是向买者征税，还是向卖者征税。
税收归宿取决于供给和需求的价格弹性。
税收负担倾向于落在缺乏弹性的市场一方身上。
3
3
4
4
7
6
7
6
10
7
10
7
14
11
14
11
7
6
7
6
7
6
2
2
10
7
10
7
10
7
10
7
15
12
15
12
17
8
17
8
17
8
17
8
24
15
29
20
30
22
30
22
31
21
31
21
33
23
33
23
38
23
38
23
39
29
39
29
44
32
44
32
51
32
51
32
41
30
41
30
