機會成本

Mankiw ch. 3 pp.47~60

為什麼現代許多國家都有「主要」工商業 ?

Interdependence

Every day you rely on

many people from around the world,

most of whom you do not

know, to provide you with the goods and services

you enjoy.

coffee from Kenya

dress shirt from China

cell phone from Taiwan

hair gel from Cleveland, OH

CHAPTER 3 INTERDEPENDENCE

Question: What is the truest definition of Globalization? Answer: Princess Diana's death.

Question: How come? Answer: An English princess with an Egyptian boyfriend crashes in a French tunnel,

driving a German car with a Dutch engine,

driven by a Belgian who was drunk on Scottish whisky, (check the bottle before you change the spelling)

followed closely by Italian Paparazzi, on Japanese motorcycles;

treated by an American doctor, using Brazilian medicines.

This is sent to you by an American, using Bill Gate's technology,

and you're probably reading this on your computer, that use Taiwanese chips,

and a Korean monitor, assembled by Bangladeshi workers

in a Singapore plant, transported by Indian lorry-drivers,

hijacked by Indonesians, unloaded by Sicilian longshoremen,

and trucked to you by Mexican illegals..... That, my friends, is Globalization.

一個國家生產的機會成本

一個國家的資源有限 如何選擇生產的產品及產量？

生產可能線 The Production Possibilities Frontier 以既定的資源，最有效率的生產方式所能

生產出來的產品組合 To illustrate the PPF, we focus on two good

s at a time and hold the quantities of all other goods and services constant.

That is, we look at a model economy in which everything remains the same (ceteris paribus) except the two goods we’re considering.

Production Possibilities and Opportunity Cost

Production Possibilities Frontier Figure 2.1 shows the

PPF for “guns” and “butter,” which stand for any pair of goods and services.

槍產量

奶油產量

Production Possibilities and Opportunity Cost

Points inside and on the frontier, such as points A, B, C, D, E, F, and Z are attainable.

Points outside the frontier are unattainable.

做得到的

做不到的

生產的效率Production Efficiency

We achieve production efficiency if we cannot produce more of one good without producing less of some other good.

生產可能線上的每一點都達到生產的效率

效率 efficiency

資源的最有效利用，無浪費 有效率的經濟體系

使用所有資源 產出 ( 現有科技下 ) 所能的最大產出

生產的效率 vs. 分配的效率

Any point inside the frontier, such as point Z, is inefficient.At such a point it is possible to produce more of one good without producing less of the other good.生產可能線內上的每一點都是生產的無效率

生產的無效率

Tradeoff ( 取捨、 交換 )Along the PPF

Every choice along the PPF involves a tradeoff.

On this PPF, we must give up( 捨 ) some guns to get more ( 取 ) butter or give up some butter to get more guns.

A move from C to D C: (2,12) D: (3,9)

The opportunity cost of 1 ton of butter is 3 units of guns.

One ton of butter costs 3 units of guns.

機會成本

A move from D to C

The opportunity cost of 3 units of guns is 1 ton of butter.

One unit of guns costs 1/3 of a ton of butter.

不論取捨的對象 ( 槍或奶油 ) ，2 點間取捨的比例 ( 機會成本 )相同

機會成本

Production Possibilities and Opportunity Cost

Because resources are not all equally productive in all activities, the PPF bows outward—is concave( 凹向原點 ).

16

Imagine an economic system with only two goods, potatoes and meat and only two people, a potato farmer and a cattle rancher

What should each person produce?

Why should these people trade?

A PARABLE FOR THE MODERN ECONOMY

18

Production Possibilities

Suppose the farmer and rancher decide not to engage in trade: Each consumes only what he or she can

produce alone. The production possibilities frontier is also

the consumption possibilities frontier. Without trade, economic gains are

diminished.

Figure 1 The Production Possibilities Frontier

Potatoes (ounces)

4

16

8

32

A

0

Meat (ounces)

(a) The Farmer’ s Production Possibilities Frontier

If there is no trade, the farmer chooses this production and consumption.

Copyright©2003 Southwestern/Thomson Learning

Figure 1 The Production Possibilities Curve

Copyright©2003 Southwestern/Thomson Learning

Potatoes (ounces)

12

24

B

0

Meat (ounces)

(b) The Rancher ’s Production Possibilities Frontier

48

24

If there is no trade, the rancher chooses this production and consumption.

Production and Consumption Without Trade

22

The farmer should produce potatoes.

The rancher should produce meat.

Specialization and Trade

Suppose instead the farmer and the rancher decide to specialize and trade… Both would be better off if they

specialize in producing the product they are more suited to produce, and then trade with each other.

Figure 2 How Trade Expands the Set of Consumption Opportunities

Copyright©2003 Southwestern/Thomson Learning

Potatoes (ounces)

4

16

5

17

8

32

A

A*

0

Meat (ounces)

(a) The Farmer’ s Production and Consumption

Farmer's production and consumption without trade

Farmer's consumption with trade

Farmer's production with trade

Figure 2 How Trade Expands the Set of Consumption Opportunities

Copyright © 2004 South-Western

Potatoes (ounces)

12

24

13

27

B

0

Meat (ounces)

(b) The Rancher’s Production and Consumption

48

24

12

18

B*

Rancher's consumption with trade

Rancher's production with trade

Rancher's production and consumption without trade

25

COMPARATIVE ADVANTAGE Differences in the costs of

production determine the following: Who should produce what? How much should be traded for each

product?

26

COMPARATIVE ADVANTAGE Two ways to measure differences in

costs of production: The number of hours required to

produce a unit of output (for example, one pound of potatoes).

The opportunity cost of sacrificing one good for another.

27

Absolute Advantage

The comparison among producers of a good according to their productivity. Describes the productivity of one person,

firm, or nation compared to that of another.

The producer that requires a smaller quantity of inputs to produce a good is said to have an absolute advantage in producing that good.

The Rancher has an absolute advantage in the production of both meat and potatoes.

Absolute Advantage The Rancher needs only 10 minutes

to produce an ounce of potatoes, whereas the Farmer needs 15 minutes.

The Rancher needs only 20 minutes to produce an ounce of meat, whereas the Farmer needs 60 minutes.

29

Opportunity Cost and Comparative Advantage Compares producers of a good according to

their opportunity cost, that is, what must be given up to obtain some item

The producer who has the smaller opportunity cost of producing a good is said to have a comparative advantage in producing that good.Who has the comparative advantage in the

production of each good?

? ?

Comparative Advantage and Trade Potato costs…

The Rancher’s opportunity cost of an ounce of potatoes is ¼ an ounce of meat.

The Farmer’s opportunity cost of an ounce of potatoes is ½ an ounce of meat.

Meat costs… The Rancher’s opportunity cost of a pound of meat

is only 4 ounces of potatoes. The Farmer’s opportunity cost of an ounce of meat

is only 2 ounces of potatoes...

Comparative Advantage and Trade…so, the Rancher has a comparative advantage in the production of meat

but the Farmer has a comparative advantage in the production of

potatoes.

比較利益法則

David Ricardo (1772-1823) 絕對利益 absolute advantage

能用較少的資源產出產品 比較利益 comparative advantage

機會成本較低的產品

33

Comparative Advantage and Trade Comparative advantage and difference

s in opportunity costs are the basis for specialized production and trade.

比較利益是貿易的基礎 Whenever potential trading parties hav

e differences in opportunity costs, they can each benefit from trade.

Gains from Trade

The price for meat

Farmer: give up 15 oz potatoes for 5 oz of meant 3 oz potato for 1 oz meat (cost less

than the 4:1 self-production ratio) Rancher: give up 5 oz meat for 15

oz potatoes 1 oz meat for 3 oz meat (get more than

the 1:2 self-production ratio)

36

Comparative Advantage and Trade Benefits of Trade

Trade can benefit everyone in a society because it allows people to specialize in activities in which they have a comparative advantage.

Gains From Trade貿易的好處是什麼？ Comparative Advantage

A person has a comparative advantage in an activity if that person can perform the activity at a lower opportunity cost than anyone else.

專業化導致有效率的資源分配

specialization fosters efficient resource allocation

分工，工人對各別技術純熟生產增加

比較利益法則 (principle of comparative advantage) 即使一國的生產力比另一國弱，但以相對

成本 (OP) 比較，它在自己較有效率的產品生產上仍有相對優勢

Ricardo ：兩國各專精於它們具相對優勢的產品，然後貿易，則兩國皆可獲利 (trade-offs ，選擇損失較少的 )

專業化導致交換(specialization leads to exchange) 專業化則人門只有自己的產品，消費的慾

望不能滿足，因而交換

Adam Smith: 分工、合作使財富增加 有位不熟悉機器使用方法的工人，本來一天勉

強可做一根針，但是用了機器後，一天可做 4800 根針 -- Adam Smith, 1776, 國富論 , 第一章，論分工

交易可以是雙贏的 (trade is a win-win situation) 排除欺騙和誤解等因素，自願的交換 (vol

untary exchange) ，使得交易雙方都獲得好處

比較利益法則

天生我才必有用

APPLICATIONS OF COMPARATIVE ADVANTAGE

Should the United States trade with other countries? Each country has many citizens with different

interests. International trade can make some individuals worse off, even as it makes the country as a whole better off. Imports—goods produced abroad and sold domestically Exports—goods produced domestically and sold abroad

Each person consumes goods and services produced by many other people both in our country and around the world.

Interdependence and trade are desirable because they allow everyone to enjoy a greater quantity and variety of goods and services.

There are two ways to compare the ability of two people producing a good. The person who can produce a good with a

smaller quantity of inputs has an absolute advantage.

The person with a smaller opportunity cost has a comparative advantage.

The gains from trade are based on comparative advantage, not absolute advantage.

Trade makes everyone better off because it allows people to specialize in those activities in which they have a comparative advantage.

The principle of comparative advantage applies to countries as well as people.

Unanswered Questions…. We made a lot of assumptions about the

quantities of each good that each country produces, trades, and consumes, and the price at which the countries trade wheat for computers.

In the real world, these quantities and prices would be determined by the preferences of consumers and the technology and resources in both countries.

We will begin to study this in the next chapter.

For now, though, our goal was only to see that trade, indeed, can make everyone better off.

CHAPTER SUMMARY Interdependence and trade allow everyone

to enjoy a greater quantity and variety of goods & services.

Comparative advantage means being able to produce a good at a lower opportunity cost. Absolute advantage means being able to produce a good with fewer inputs.

When people – or countries – specialize in the goods in which they have a comparative advantage, the economic “pie” grows and trade can make everyone better off.

摘要

機會成本 生產可能線 邊際成本

比較利益 雙贏的貿易

concave ( 凹向原點 ) vs. convex (凸向原點 )

concave ( 凹面 ) convex (凸面 )

The outward bow of the PPF means that as the quantity produced of each good increases, so does its opportunity cost.

凹向原點的生產可能線代表機會成本遞增

The PPF and Marginal Cost 邊際成本

The PPF determines opportunity cost. The marginal cost of a good or service is th

e opportunity cost of producing one more unit of it.

邊際成本 : 增加一單位產品所需付出的機會成本

As we move along the PPF in part a (shown here) the opportunity cost and the marginal cost of butter increases.

邊際成本遞增

the marginal cost of butter.

邊際成本隨產量遞增 邊

際成本

奶油產量

成本遞增定理

為什麼邊際成本遞增？ 因為資源通常有其專門性 (specialized)

Using Resources Efficiently 效率 Efficient Use of Resources

When we cannot produce more of any one good without giving up some other good, we have achieved production efficiency, and we are producing at a point on the PPF. PPF 上任一點皆符合生產效率

When we cannot produce more of any one good without giving up some other good that we value more highly, we have achieved allocative efficiency, and we are producing at the point on the PPF that we prefer above all other points. 分配的效率還需考慮偏好

分配的效率

當邊際成本 = 邊際效益，達到分配的效率

邊際效益 marginal benefit 消費者主觀的認知

邊際成本遞增 邊際效益遞減

We get more value from our resources by producing more butter.

On the PPF at point A, we are producing too many guns, and we are better off moving along the PPF to produce more butter.

If we produce less than 2.5 tons of butter, marginal benefit exceeds marginal cost.

We cannot get more value from our resources.

On the PPF at point B, we are producing the efficient quantities of guns and butter.

If we produce exactly 2.5 tons of butter, marginal cost equals marginal benefit.

Recreation(hours per day)

GPA(points)

?

生產的機會成本可以從 PPF 的斜率來決定 Y/ X = (guns)/ (butter) 斜率代表生產的機會成本

為了多生產 100輛車，必須放棄 200台電腦

電腦 / 車 = 200/100 = 2

生產可能線的形狀有特殊意義

Shape: concave

Principle of increasing costs: production of one good opportunity cost of producing another unit

Reason: inputs tend to be specialized( 專業化 )

Economic Growth The expansion of production possibilities—and

increase in the standard of living—is called economic growth.

Two key factors influence economic growth: Technological change Capital accumulation Technological change is the development of

new goods and of better ways of producing goods and services.

Capital accumulation is the growth of capital resources, which includes human capital.

Economic Growth

The Cost of Economic Growth To use resources in research and

development and to produce new capital, we must decrease our production of consumption goods and services.

Economic Growth

By using some resources to produce butter-making machines, the PPF shifts outward in the future.

Economic Growth

Economic Growth in the United States and Hong Kong In 1960, Hong Kong’s

production possibilities (per person) were much smaller than those in the United States.

Economic Growth By 2000, Hong Kong’s

production possibilities (per person) were still smaller than those in the United States.

But Hong Kong grew faster than the United States grew by devoting more of its resources to capital accumulation.

Dynamic Comparative Advantage 比較利益是貿易的基礎

Learning-by-doing occurs when a person (or nation) specializes and by repeatedly producing a particular good or service becomes more productive in that activity and lowers its opportunity cost of producing that good over time.

Dynamic comparative advantage occurs when a person (or nation) gains a comparative advantage from learning-by-doing.

4

Tom’s PPF

CD

盒(

千

個)

CD (千個 )

Tom 的工廠生產 CD與 CD盒

Tom 工廠的生產可能一小時生產 4000 CD 或 1333 個盒子

1 張 CD 的機會成本 : 1/3 個盒子 (1333/4000)1 個盒子 的機會成本 : 3張 CD(4000/1333)

1

4

Nancy’s PPF

CD

盒(

千

個)

CD (千個 )

Nancy 的工廠生產 CD與 CD盒

Nancy 工廠的生產可能一小時生產 4000 個盒子 或 1333CD

1 張 CD 的機會成本 : 3 個盒子 (4000/1333) 1 個盒子 的機會成本 : 1/3張 CD (1333/4000)

4

4

Tom’s PPF

盒子(

千

個)

CD (千個 )

每小時

1 張 CD 的機會成本Nancy 3 個盒子 Tom 1/3 個盒子

1 個盒子 的機會成本 Nancy 1/3張 CD Tom 3張 CD

4

Nancy’s PPF Nancy 盒子 有比較利益 Tom CD 有比較利益

絕對利益與比較利益 絕對利益

Nancy 生產盒子 有絕對利益 因為 1 個盒子 的絕對成本 Nancy: 0.015 分鐘 Tom: 0.045 分鐘

比較利益

Nancy 生產盒子 有比較利益 因為 1 個盒子 的機會成本 Nancy: 1/3張 CD Tom: 3張 CD

兩人交換 CD與盒子 的比例 :價格1 個盒子 的機會成本

Nancy: 1/3張 CD Tom: 3張 CD

當 Nancy 以盒子 向 Tom 交換時，必然要換來 1/3張以上的 CD 才比自己做合算

Tom 則認定，只要 1 個盒子需 要 3張 CD 以下便可以

( 多於自己所能生產 )

Achieving the Gains from Trade If Tom and Nancy exchange cases

and discs at one case per disc (one disc per case) they exchange along the Trade line and end up with 2000 CD units each—double what they can achieve without specialization and trade.

Each double what they can achieve without specialization and trade. 貿易使總產量增加，個別的消費就可能超過不貿易的情形

有絕對利益不一定有比較利益

Tom 工廠的生產可能提高

原本 : 一小時生產 4000 CD 或 1333 個盒子

現在 : 一小時生產 16000 CD 或 5332 個盒子

1 張 CD 的機會成本仍是 : 1/3 個盒子 (1333/4000)但絕對成本都是原來的 1/4: 0.00375

Tom 生產盒子 有絕對利益 Nancy 生產盒子 仍有比較利益

法國高中生的畢業考題

“給予的目的在於獲得”，這是否是一切交流的原則？

The Market Economy 市場經濟

Circular Flows in the Market Economy A circular flow diagram, like Figure

2.10, illustrates how households and firms interact in the market economy.

Goods and services and factors of production flow in one direction.

And money flows in the opposite direction.

Coordinating Decisions Prices coor

dinate decisions in markets.

價格機能

交易可以是雙贏的 (trade is a win-win situation) 經由分工、合作 ( 貿易 )Nancy 和 Tom 所擁有的 CD 與盒子會多於自己所能生產的

支出收益

出售產品 購買產品

支付工資、

地租、利息等

所得

提供勞動、土地、資本

投入生產

產品市場

廠商 家戶

要素市場