Transcript Figure 3-1

Chapter 3 特定要素模型（Specific
Factors and Income Distribution）
 导论（Introduction）
 特定要素模型（The Specific Factors Model）
 特定要素模型中国际贸易（International Trade




in the Specific Factors Model）
收入分配与贸易得益（Income Distribution
and the Gains from Trade）
贸易的政治经济学（The Political Economy of
Trade: A Preliminary View）
总结（Summary）
附录（Appendix: Further Details on Specific
Factors）
1
Introduction导论
 Trade has substantial effects on the income
distribution within each trading nation.不同国家
之间的贸易对收入分配产生较大的影响
 There are two main reasons why international
trade has strong effects on the distribution of
income:两个主要原因
 Resources cannot move immediately or costlessly
from one industry to another.资源不能无成本和快速地
从一个行业转向另外一个行业。
 Industries differ in the factors of production they
demand。行业对生产要素的需要不同
 The specific factors model allows trade to
affect income distribution.特定要素模型考虑了贸
易对收入分配的影响。
2
3-1 The Specific Factors Model
 Assumptions of the Model（模型假设）
 Assume that we are dealing with one economy that can
produce two goods, manufactures and food.（一个国家能生产
两种商品：制造品和粮食）
 There are three factors of production; labor (L), capital (K) and
land (T for terrain).（三种生产要素）
 Manufactures are produced using capital and labor (but not
land).（生产制造品只使用劳动力和资本，不需要土地）
 Food is produced using land and labor (but not capital).
 Labor is therefore a mobile factor that can be used in either sector.
（粮食生产只需要劳动力和土地，劳动力可以在两个生产部门流动）
 Land and capital are both spe‘cific factors that can be used only in
the production of one good.（土地和资本是特定要素）
 Perfect Competition prevails in all markets.（完全竞争）
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 How much of each good does the economy produce?一
个经济体不同商品各生产多少
 The economy’s output of manufactures depends on how much
capital and labor are used in that sector.生产多少依赖于要素投
入的多少
 This relationship is summarized by a production
function.产出与投入之间的关系可由生产函数来概括。
 The production function for good X gives the maximum
quantities of good X that a firm can produce with
various amounts of factor inputs.商品X的生产函数是不
同要素投入所能生产出商品X的最大数量。
 For instance, the production function for manufactures (food)
tells us the quantity of manufactures (food) that can be
produced given any input of labor and capital (land).
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 制造品的生产函数The production function for
manufactures is given by
QM = QM (K, LM)
(3-1)
where:
 QM is the economy’s output of manufactures制造品产出
 K is the economy’s capital stock资本存量
 LM is the labor force employed in manufactures制造行业中劳动
力的使用量
 粮食生产函数The production function for food is given
by
QF = QF (T, LF)
(3-2)
where:
 QF is the economy’s output of food粮食产出
 T is the economy’s supply of land土地供应量
 LF is the labor force employed in food粮食生产使用的劳动量
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 约束条件The full employment of labor condition
requires that the economy-wide supply of labor
must equal the labor employed in food plus the
labor employed in manufactures:充分就业要求两
部门使用的劳动力与总劳动力供应相等
LM + LF = L
(3-3)
 We can use these equations and derive the
production possibilities frontier of the economy.
我们可以根据这些等式推导出生产可能性边界
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 Production Possibilities生产可能性边界
To analyze the economy’s production
possibilities, we need only to ask how the
economy’s mix of output changes as labor is
shifted from one sector to the other.为了分析经
济体的生产可能性，我们需要知道当劳动力从一
个部门移向另外一个部门时产出组合将如何变化。
Figure 3-1 illustrates the production function for
manufactures.
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Figure 3-1: The Production Function for Manufactures
制造业的生产可能性边界
Output产出, QM
QM = QM (K, LM)
Labor input劳动投入, LM
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 递减的边际收益The shape of the production function
reflects the law of diminishing marginal returns.生产函
数的形状反映了递减的边际收益
 Adding one worker to the production process (without increasing
the amount of capital) means that each worker has less capital to
work with.增加一个劳动进行生产意味着每个工人将占用更少的资
本
 Therefore, each additional unit of labor will add less to the
production of output than the last.因此，将导致产出增量减少
 Figure 3-2 shows the marginal product of labor, which
is the increase in output that corresponds to an extra unit
of labor.
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Figure 3-2: The Marginal Product of Labor
Marginal product
of labor, MPLM
MPLM
Labor input, LM
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Figure 3-3: The Production Possibility Frontier in the Specific Factors Model
Production function
for food粮食生产函数
QF =QF(K, LF)
粮食产量Output of food,
QF (increasing ) 生产可能性边界Economy’s product
possibility frontier (PP)
Q 2F
1'
2'
3'
制造品产量Output
粮食生产投入的
Q2 M
L2F
PP
of manufactures,
劳动Labor
QM (increasing
input in food,
2
LM
1
)
LF (increasing
2
)
制造品生产函数Product
3
劳动力配置Economy’s allocation
AA
for manufactures
of labor (AA)
制造品投入的劳动量Labor Q
input
M =QM(K, LM)
in manufactures,
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LM (increasing )
 价格，工资与劳动配置（Prices, Wages, and
Labor Allocation）
 各个部门将投入多少劳动？（How much labor will
be employed in each sector?）
 要问答这个问题必须了解劳动力市场的供求（To answer
the above question we need to look at supply and
demand in the labor market.）
 劳动需求Demand for labor:
 在每个部门，作为利润最大化的雇主，将使雇佣的劳动国
数量处于当增加一个劳动者所带来的利润等于工资支出的
位置。In each sector, profit-maximizing employers will
demand labor up to the point where the value produced
by an additional person-hour equals the cost of
employing that hour.
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制造部门劳动力需求曲线可以表达为:(The
demand curve for labor in the manufacturing
sector can be written:)
MPLM x PM = w
(3-4)
即制造部门的工资等于劳动边际产品的价值
（The wage equals the value of the marginal
product of labor in manufacturing.）
The demand curve for labor in the food sector
can be written:
MPLF x PF = w
(3-5)
The wage rate equals the value of the marginal
product of labor in food.
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The wage rate must be the same in both
sectors, because of the assumption that labor
is freely mobile between sectors.（由于劳动
力是自由流动的，所以两个生产部门工资率必
须相等）
 The wage rate is determined by the
requirement that total labor demand equal
total labor supply:
LM + LF = L
(3-6)
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Figure 3-4: The Allocation of Labor
Wage rate, W
Wage rate, W
1
PF X MPLF
(Demand curve
for labor in food)
W1
PM X MPLM
(Demand curve for labor in
manufacturing)
Labor used in
manufactures, LM
L1M
Labor used
in food, LF
L1F
总劳动力供应Total labor supply, L
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 At the production point the production possibility
frontier must be tangent to a line whose slope is
minus the price of manufactures divided by that
of food.（在生产点上，生产可能性边界一定和一
条斜率等于负的制造品价格除以粮食价格的直线
相切）
 Relationship between relative prices and output:
-MPLF/MPLM = -PM/PF
(3-7)
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Figure 3-5: Production in the Specific Factors Model
（社会在生产可能性边界上斜率负的制造品相对价格的点上进行生
产）
Output of food, QF
Slope = -(PM /PF)1
1
Q1 F
PP
Q1 M
Output of manufactures, QM
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What happens to the allocation of labor and the
distribution of income when the prices of food
and manufactures change?（当两种产品价格发
生变化时，劳动力和收入如何变化？）
Two cases:
 An equal proportional change in prices（价格同比例
变化）
 A change in relative prices（相对价格变化）
18
Figure 3-6: An Equal Proportional Increase in the Prices of Manufactures and Food
同比例变化的情况
2
PM X MPLM
Wage rate, W
PF 2 X MPLF
Wage rate, W
1
PM X MPLM
W2
PM
increases
10%
PF increases
10%
2
PF 1 X MPLF
10%
wage
increase
1
W1
Labor used in
manufactures, LM
Labor used
in food, LF
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When both prices change in the same
proportion, no real changes occur.
 The wage rate (w) rises in the same
proportion as the prices, so real wages
(i.e. the ratios of the wage rate to the
prices of goods) are unaffected.
 The real incomes of capital owners and
landowners also remain the same.
 没有真实变化，变化只是名义工资和名义
价格，真实收入和劳动力雇佣数没有任何
变化。
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 When only PM rises, labor shifts from the food sector to
the manufacturing sector and the output of
manufactures rises while that of food falls.当只有PM 升
高时，劳动力从粮食部门转移到制造品部门，制造品部
门产出提高，而粮食部门产出减少。
 The wage rate (w) does not rise as much as PM since
manufacturing employment increases and thus the
marginal product of labor in that sector falls.工资率没有
价格升高那么多，原因是：劳动边际收益递减。
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Figure 3-7: A Rise in the Price of Manufactures
制造业部门价格上升
Wage rate, W
7%
upward
shift in
labor
demand
Wage
W2
rate
rises by W 1
less than
7%
1
PF X MPLF
Wage rate, W
2
1
PM 2 X MPLM
PM 1 X MPLM
Labor used in
manufactures, LM
Amount of labor
shifted from food
to manufactures
Labor used
in food, LF
22
Figure 3-8: The Response of Output to a Change in the
Relative Price of Manufactures
制造品相对价格变化引起总产出变化
Output of food, QF
Slope = - (PM /PF)1
Q1F
1
Q2F
2
Slope = - (PM /PF) 2
PP
Q1 M
Q2 M
Output of
manufactures, QM
23
Figure 3-9: Determination of Relative Prices
Relative price 相对价格
of manufactures, PM /PF
RS
1
(PM /PF
)1
RD
(QM /QF )1
Relative quantity相对数量
of manufactures, QM/QF
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 相对价格与收入分配Relative Prices and the
Distribution of Income
 Suppose that PM increases by 10%. Then, we
would expect the wage to rise by less than 10%,
say by 5%.
 What is the economic effect of this price increase
on the incomes of the following three groups?相对
价格变化对不同得益集团收入的经济影响是如何的
呢？
 Workers工人
 Owners of capital资本所有者
 Owners of land土地所有者
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 Workers:
 We cannot say whether workers are better or worse off; this
depends on the relative importance of manufactures and
food in workers’ consumption.取决于工人的消费偏好，即制
造品和粮食在他们消费中所占比例更多。
 Owners of capital:
 They are definitely better off.以制造品衡量的实际工资率下降。
即资本所有者收益上升大于价格上升幅度。
 Landowners:
 They are definitely worse off.以粮食衡量的实际工资率上升；
制造品的价格上升。
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3-2 International Trade in the
Specific Factors Model特定要素模型中
的国际贸易
 Assumptions of the model
 Assume that both countries (Japan and America) have
the same relative demand curve.在给定的相对价格下，
相对需求民相等（相同的相对需求曲线））
 Therefore, the only source of international trade is the
differences in relative supply. The relative supply might
differ because the countries could differ in:相对供应不
同：国际贸易的唯一来源
 Technology
 Factors of production (capital, land, labor)
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 资源与相对供应（Resources and Relative
Supply）
What are the effects of an increase in the
supply of capital stock on the outputs of
manufactures and food?当资本存量的供应增加
时，对制造品和粮食产出的影响是什么呢？
 A country with a lot of capital and not much land will
tend to produce a high ratio of manufactures to food
at any given prices.价格一定时，拥有大量资本和少量
土地的国家将生产更多 的制造品和少量的粮食。
28
Figure 3-10: Changing the Capital Stock
假如日本资本存量增加，其影响如何呢？
Wage rate, W
Increase
in capital
stock, K
PF 1 X MPLF
Wage rate, W
2
W2
1
W1
PM X MPLM2
PM X MPLM1
Labor used in
manufactures, LM
Amount of labor
shifted from food to
manufactures
Labor used
in food, LF
29
 An increase in the supply of capital would shift the
relative supply curve to the right.（资本增加使制造部门
相对供应曲线右移）
 An increase in the supply of land would shift the relative
supply curve to the left.（土地增加使制造部门相对供应
曲线左移）
 What about the effect of an increase in the labor force?
（劳动力增加的效应又如何呢？）
 The effect on relative output is ambiguous, although both
outputs increase.两部门产出均增加，所以结论是模糊的、不确
定的。
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 Trade and Relative Prices贸易和相对价
格
Suppose that Japan has more capital per
worker than America, while America has
more land per worker than Japan.假定
 As a result, the pretrade relative price of
manufactures in Japan is lower than the
pretrade relative price in America.
International trade leads to a convergence
of relative prices.国际贸易导致相对价格趋
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Figure 3-11: Trade and Relative Prices
Relative price of
manufactures, PM /PF
RSA
RSWORLD
(PM /PF )A
RSJ
(PM /PF )W
(PM /PF )J
RDWORLD
Relative quantity of
manufactures, QM/QF
32
 The Pattern of Trade贸易模式
 In a country that cannot trade, the output of a good must equal
its consumption. 封闭经济下，产出等于消费。

DM=QM DF=QF
 International trade makes it possible for the mix of manufactures
and food consumed to differ from the mix produced. 贸易使得一
个国家可以消费不同于产出的组合。
 A country cannot spend more than it earns. 消费不能超过收入。
 PM*DM+PF*DF=PM*QM +PF*QF
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Figure 3-12: The Budget Constraint for a Trading Economy
参与贸易国的预算约束
Consumption of food, DF
Output of food, QF
Budget constraint
(slope = -PM/PF)
1
Q1 F
Production possibility curve
Q1 M
Consumption of manufactures, DM
Output of manufactures, QM
34
Figure 3-13: Trading Equilibrium
Quantity of
food
Quantity of
food
Japanese budget constraint
American budget constraint
America’s QA
F
food
A
exports D F
Japan’s DJ
F
food
imports QJF
DJM QJM Quantity of
manufactures
Japan’s
manufactures
exports
QAM DAM
America’s
manufactures
imports
Quantity of
manufactures
35
3-3 Income Distribution and the
Gains from Trade收入分配与贸易得益
 To assess the effects of trade on particular groups, the key
point is that international trade shifts the relative price of
manufactures and food.
 Trade benefits the factor that is specific to the export sector
of each country, but hurts the factor that is specific to the
import-competing sectors.Trade has ambiguous effects on
mobile factors.
 结论： 贸易使出口部门特定要素所有者受益，使进口产品
竞争部门特定要素的所有者受损，而对流动要素所有者的影
响具有不确定性。
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 Could those who gain from trade compensate
those who lose, and still be better off themselves?
贸易收益是否一定大于贸易损失呢？
 If so, then trade is potentially a source of gain to
everyone.
 The fundamental reason why trade potentially
benefits a country is that it expands the
economy’s choices.贸易对一国具有潜在收益的
基本原因是增加该经济体的消费选择。
 This expansion of choice means that it is always
possible to redistribute income in such a way that
everyone gains from trade.
37
Figure 3-14: Trade Expands the Economy’s Consumption Possibilities
Consumption of food, DF
Output of food, QF
2
Q1
1
F
Budget constraint
(slope = - PM/PF)
PP
Q1 M
Consumption of manufactures, DM
Output of manufactures, QM
38
3-4 The Political Economy of Trade:
A Preliminary View
 Trade often produces losers as well as winners.
 Optimal Trade Policy
 The government must somehow weigh one person’s
gain against another person’s loss.
 Some groups need special treatment because they are already
relatively poor (e.g., shoe and garment workers in the United
States).
 Most economists remain strongly in favor of more or less free
trade.
 Any realistic understanding of how trade policy is
determined must look at the actual motivations of policy.
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 Income Distribution and Trade Politics
Those who gain from trade are a much
less concentrated, informed, and organized
group than those who lose.
 Example: Consumers and producers in the U.S.
sugar industry
40
Summary
 International trade often has strong effects on
the distribution of income within countries, so
that it often produces losers as well as winners.
 Income distribution effects arise for two
reasons:
 Factors of production cannot move instantaneously
and costlessly from one industry to another.
 Changes in an economy’s output mix have
differential effects on the demand for different
factors of production.
41
Summary
 A useful model of income distribution effects of
international trade is the specific-factors model.
 In this model, differences in resources can cause
countries to have different relative supply curves, and
thus cause international trade.
 In the specific factors model, factors specific to export
sectors in each country gain from trade, while factors
specific to import-competing sectors lose.
 Mobile factors that can work in either sector may either
gain or lose.
42
Summary
 Trade nonetheless produces overall gains in
the sense that those who gain could in
principle compensate those who lose while
still remaining better off than before.
43
Appendix:Further Details on
Specific Factors
Figure 3A-1: Showing that Output Is Equal to the Area Under the
Marginal Product Curve
Marginal Product of
Labor, MPLM
MPLM
dLM
Labor input, LM
44
Appendix:Further Details on
Specific Factors
Figure 3A-2: The Distribution of Income Within
the Manufacturing Sector
Marginal Product of
Labor, MPLM
Income of
capitalists
w/PM
Wages
MPLM
Labor input, LM
45
Appendix:Further Details on
Specific Factors
Figure 3A-3: A Rise in PM Benefits the Owners of Capital
Marginal Product of
Labor, MPLM
Increase in
capitalists’ income
(w/PM)1
(w/PM)2
MPLM
Labor input, LM
46
Appendix:Further Details on Specific
Factors
Figure 3A-4: A Rise in PM Hurts Landowners
Marginal Product of
Labor, MPLF
Decline in landowners’
income
(w/PF)2
(w/PF)1
MPLF
Labor input, LF
47
Reading
 杨小凯、张永生（2001）：新贸易理论、比
较利益理论及其经验研究的新成果：文献综
述，《经济学（季刊）》10月，第1卷第1期
 程祖伟(2004):正确解读萨缪尔森- 琼斯的特
定要素贸易理论，《经济经纬》第3期
48
Question
 P61,3
49