Download 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）
3
 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).
4
 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
5
 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
6
 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.
7
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
8
 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.
9
Figure 3-2: The Marginal Product of Labor
Marginal product
of labor, MPLM
MPLM
Labor input, LM
10
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,
11
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.
12
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.
13
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)
14
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
15
 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)
16
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
17
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
19
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。
20
 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。
21
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
24
 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
25
 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。
26
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)
27
 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。
30
 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
31
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
33
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。
36
 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.
39
 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