# 西经高鸿业第三版lecture10

LECTURE10 一般均衡和福利经济学

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General Equilibrium Analysis
Two Interdependent Markets--Moving to General Equilibrium
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Scenario
? The competitive markets of:
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Videocassette rentals Movie theater tickets

Two Interdependent Markets: Movie Tickets and Videocassette Rentals
Price Assume the government imposes a \$1 tax on each movie ticket. Price General Equilibrium Analysis: Increase in movie ticket prices increases demand for videos.

S*M

SM
\$3.50 \$3.00

SV

\$6.35

\$6.00

D’V

DM
Q’M QM
Number of Movie Tickets

DV
QV Q’V
Number of Videos

Two Interdependent Markets: Movie Tickets and Videocassette Rentals
Price The increase in the price of videos increases the demand for movies. Price The Feedback effects continue.

S*M
\$6.82 \$6.75 \$6.35

SM
\$3.58 \$3.50 \$3.00

SV

D*V
D’V

\$6.00

D*M D’M DM
Q’M Q”M Q*M QM

DV
QV Q’V Q*V
Number of Videos

Number of Movie Tickets

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? 任何厂商不存在规模报酬递增、每种商品的生产至

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? 拍卖人报出一组价格，家庭和厂商根据自身的需求

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? 两个消费者；两种商品；两人知道彼此的偏好（信息对称）；

0交易费用。

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? 两消费者的边际替代率相等时实现，这在埃奇沃斯盒子里体

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? 埃奇沃斯盒子中所有两人无差异曲线相切的切点集合，它显

Efficiency in Exchange
10F 6C
A: UJ1 = UK1, but the MRS is not equal. All combinations in the shaded area are preferred to A.

Karen’s Food

0K

James’s Clothing

D

C
B

Karen’s Clothing

UJ3
A

UJ2 UJ1 6C 10F

UK3 UK2 0J
James’s Food

UK1

Efficiency in Exchange
10F 6C Is B efficient? Hint: is the MRS equal at B?
James’s Clothing Karen’s Food

0K

D

C

Karen’s Clothing

Is C efficient? and D?

B

UJ3
A

UJ2 UJ1 6C 10F

UK3 UK2 0J
James’s Food

UK1

The Contract Curve
E, F, & G are Pareto efficient . If a change improves efficiency, everyone benefits. Karen’s Food

0K

Contract Curve

G
James’s Clothing

F

Karen’s Clothing

E

0J

James’s Food

J K MRSFC ? MRSFC

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Efficiency in Production
50L 30K
Efficiency ?A is inefficient Labor in clothing production ? is preferred to A 20L 40LShaded area 30L 10L ?B and C are efficient ?The production contract curve shows 80F all combinations that are efficient

0C

25C 10C
20K
Capital in food production Each point measures inputs 10K to the production A: 35L and 5K--Food B: 15L and 25K--Clothing Each isoquant shows input combinations for a given output Food: 50, 60, & 80 Clothing: 10, 25, & 30

D
10K
Capital in clothing production

30C

C

B
A 60F 50F
20L 30L 40L

20K

0F

10L

30K 50L

Labor in Food Production

C D MRTSLK ? MRTSLK

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MRT ? dC MCF ? dF MCC

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? 向下倾斜：两种最优产出的变化必然相反。否则会怎

dC dC dC d (L ? K ) d (L ? K ) MRT ? ? ? ? dF dF d (L ? K ) dF d (L ? K )
dC d (L ? K )
-生产C的边际生产力， 产出F增加，根据边际报酬递减，

dF d (L ? K )
-生产F的边际生产力。 产出C减少，根据编辑报酬递减， dC d (L ? K )

dF d (L ? K )

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MRSFC ? MRTFC

Output Efficiency
Clothing (units)
60
MRS = MRT

Production Possibilities Frontier

C

Indifference Curve

100

Food (Units)

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Karen’s Food

10F

0K Price Line P
Begin at A: Each James buys 2C and sells 2F Each James would move from Uj1 to Uj2, which is preferred (A to C).

6C
PP’ is the price line and shows possible combinations; slope is -1

James’s Clothing
Begin at A: Each Karen buys 2F and sells 2C. Each Karen would move from UK1 to UK2, which is preferred (A to C).

C

Karen’s Clothing

UJ2

A
UK2 UK1

UJ1

P’ 10F

6C

0J

James’s Food

Karen’s Food

10F

0K Price Line P
At the prices chosen: Quantity food demanded (Karen) equals quantity food supplied (James)--competitive equilibrium.

6C

James’s Clothing
At the prices chosen: Quantity clothing demanded (James) equals quantity clothing supplied (Karen) --competitive equilibrium.

C

Karen’s Clothing

UJ2

A
UK2 UK1

UJ1

P’ 10F

6C

0J

James’s Food

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J K MRSFC ? PC / PF ? MRSFC

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MCF PF MRT ? ? ? MRS MCC PC

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UB

W2 W1 W0

E

UA

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? 平等化的直接效率损失：为获得更大程度的平等

Karen’s Utility OJ
*Any point inside the frontier (H) is inefficient. *Combinations beyond the frontier (L) are not obtainable.

E

L

Lets compare H to E and F.

F H G

*Movement from one combination to another (E to F) reduces one persons utility. *All points on the frontier are efficient.

OK James’s Utility

E & F are efficient. Compared to H, E & F make one person
better off without making the other worse off.
Karen’s Utility

OJ
E

F H G

OK
James’s Utility

Is H equitable?
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Karen’s Utility

Assume the only choices are H & G Is G more equitable? It depends on perspective.
? At G James total utility > Karen’s total utility

OJ
E

F H G

OK
James’s Utility

Is H equitable?
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Karen’s Utility

Assume the only choices are H & G Is G more equitable? It depends on perspective.
? H may be more equitable because the distribution is

OJ
E

F H G

more equal, therefore, an inefficient allocation may be more equitable.

OK
James’s Utility

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? 在决定收入分配时首先考虑效率，将之作为收入

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? 减少和消除不合理收入、促进机会均等、限制某

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