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    1

    Chapter 12

    GENERAL EQUILIBRIUM AND

    WELFARE

    Copyright 2005 by South-Western, a division of Thomson Learning. All rights reserved.

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    2

    Perfectly Competitive

    Price System We will assume that all markets are

    perfectly competitive

    there is some large number of homogeneousgoods in the economy both consumption goods and factors of

    production

    each good has an equilibrium price there are no transaction or transportation

    costs

    individuals and firms have perfect information

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    3

    Law of One Price A homogeneous good trades at thesame price no matter who buys it or

    who sells it

    if one good traded at two different prices,

    demanders would rush to buy the good

    where it was cheaper and firms would try

    to sell their output where the price washigher

    these actions would tend to equalize the price

    of the good

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    4

    Assumptions of Perfect

    Competition There are a large number of people

    buying any one good

    each person takes all prices as given andseeks to maximize utility given his budget

    constraint

    There are a large number of firmsproducing each good

    each firm takes all prices as given and

    attempts to maximize profits

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    5

    General Equilibrium Assume that there are only two goods,x

    and y

    All individuals are assumed to haveidentical preferences

    represented by an indifference map

    The production possibility curve can beused to show how outputs and inputs are

    related

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    6

    Edgeworth Box Diagram Construction of the production possibility

    curve forxand ystarts with the

    assumption that the amounts of kand l

    are fixed

    An Edgeworth box shows every possible

    way the existing kand lmight be used to

    producexand y any point in the box represents a fully

    employed allocation of the available

    resources toxand y

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    9

    Edgeworth Box Diagram We will use isoquant maps for the two

    goods

    the isoquant map for goodxuses Oxas theorigin

    the isoquant map for good yuses Oyas the

    origin

    The efficient allocations will occur where

    the isoquants are tangent to one another

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    10

    Edgeworth Box Diagram

    Ox

    Oy

    Total Labor

    T

    otalCapital

    x2

    x1

    y1

    y2

    A

    PointAis inefficient because, by moving along y1, we can increase

    xfromx1tox2while holding yconstant

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    11

    Edgeworth Box Diagram

    Ox

    Oy

    Total Labor

    T

    otalCapital

    x2

    x1

    y1

    y2

    A

    We could also increase yfrom y1to y2while holdingxconstant

    by moving alongx1

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    13

    Production Possibility Frontier

    The locus of efficient points shows the

    maximum output of ythat can be

    produced for any level ofx we can use this information to construct a

    production possibility frontier

    shows the alternative outputs ofxand ythat

    can be produced with the fixed capital and

    labor inputs that are employed efficiently

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    15

    Rate of Product Transformation

    The rate of product transformation (RPT)

    between two outputs is the negative of

    the slope of the production possibilityfrontier

    frontierypossibilit

    productionofslope)for(of yxRPT

    )(along)for(of yxOOdx

    dyyxRPT

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    16

    Rate of Product Transformation

    The rate of product transformation shows

    howxcan be technically traded for y

    while continuing to keep the availableproductive inputs efficiently employed

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    17

    Shape of the Production

    Possibility Frontier

    The production possibility frontier shown

    earlier exhibited an increasing RPT this concave shape will characterize most

    production situations

    RPTis equal to the ratio of MCxto MC

    y

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    18

    Shape of the Production

    Possibility Frontier Suppose that the costs of any output

    combination are C(x,y)

    along the production possibility frontier,

    C(x,y) is constant

    We can write the total differential of the

    cost function as

    0

    dy

    y

    Cdx

    x

    CdC

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    19

    Shape of the Production

    Possibility Frontier Rewriting, we get

    y

    xyx

    MCMC

    yCxCOO

    dxdyRPT

    //)(along

    The RPTis a measure of the relative

    marginal costs of the two goods

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    20

    Shape of the Production

    Possibility Frontier As production ofxrises and production

    of yfalls, the ratio of MCxto MC

    yrises

    this occurs if both goods are produced

    under diminishing returns

    increasing the production ofxraises MCx, while

    reducing the production of ylowers MCy this could also occur if some inputs were

    more suited forxproduction than for y

    production

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    21

    Shape of the Production

    Possibility Frontier But we have assumed that inputs are

    homogeneous

    We need an explanation that allows

    homogeneous inputs and constant

    returns to scale

    The production possibility frontier will be

    concave if goodsxand yuse inputs in

    different proportions

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    22

    Opportunity Cost

    The production possibility frontier

    demonstrates that there are many

    possible efficient combinations of twogoods

    Producing more of one good

    necessitates lowering the production ofthe other good

    this is what economists mean by opportunity

    cost

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    23

    Opportunity Cost

    The opportunity cost of one more unit of

    xis the reduction in ythat this entails

    Thus, the opportunity cost is bestmeasured as the RPT(ofxfor y) at the

    prevailing point on the production

    possibility frontier this opportunity cost rises as morexis

    produced

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    24

    Concavity of the Production

    Possibility Frontier Suppose that the production ofxand y

    depends only on labor and the production

    functions are5.0)( xxfx ll

    5.0)( yyfy ll

    If labor supply is fixed at 100, then

    lx+ ly= 100

    The production possibility frontier is

    x2+ y2= 100 forx,y0

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    25

    Concavity of the Production

    Possibility Frontier The RPTcan be calculated by taking the

    total differential:

    y

    x

    y

    x

    dx

    dyRPTydyxdx

    2

    )2(or022

    The slope of the production possibility

    frontier increases asxoutput increases the frontier is concave

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    26

    Determination of

    Equilibrium Prices

    We can use the production possibility

    frontier along with a set of indifferencecurves to show how equilibrium prices

    are determined

    the indifference curves represent

    individuals preferences for the two goods

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    28

    Determination of

    Equilibrium Prices

    Quantity ofx

    Quantity of y

    y1

    x1

    U1

    U2

    U3

    y

    x

    p

    pslope

    C

    C

    The price ofxwill rise andthe price of ywill fall

    x1

    y1

    There is excess demand forxand

    excess supply of y

    excess

    supply

    excess demand

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    29

    Determination of

    Equilibrium Prices

    Quantity ofx

    Quantity of y

    y1

    x1

    U1

    U2

    U3

    y

    x

    p

    pslope

    C

    C

    x1

    y1

    The equilibrium output will

    bex1* and y1*y1*

    x1*

    The equilibrium prices will

    bepx* andpy*

    C*

    C*

    **slope

    y

    x

    pp

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    30

    Comparative Statics Analysis

    The equilibrium price ratio will tend to

    persist until either preferences or

    production technologies change If preferences were to shift toward good

    x,px/pywould rise and morexand less

    ywould be produced we would move in a clockwise direction

    along the production possibility frontier

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    31

    Comparative Statics Analysis

    Technical progress in the production of

    goodxwill shift the production

    possibility curve outward this will lower the relative price ofx

    morexwill be consumed

    ifxis a normal good

    the effect on yis ambiguous

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    32

    Technical Progress in the

    Production of x

    Quantity ofx

    Quantity of y

    U1

    U2

    U3

    x1*

    The relative price ofxwill fall

    Morexwill be consumed

    x2*

    Technical progress in the production

    ofxwill shift the production possibility

    curve out

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    33

    General Equilibrium Pricing Suppose that the production possibility

    frontier can be represented by

    x2+ y2= 100

    Suppose also that the communitys

    preferences can be represented by

    U(x,y) =x0.5y0.5

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    34

    General Equilibrium Pricing Profit-maximizing firms will equate RPT

    and the ratio ofpx/py

    y

    x

    pp

    yxRPT

    Utility maximization requires that

    y

    x

    p

    p

    x

    yMRS

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    35

    General Equilibrium Pricing Equilibrium requires that firms and

    individuals face the same price ratio

    MRSxy

    pp

    yxRPT

    y

    x

    or

    x* = y*

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    36

    The Corn Laws Debate High tariffs on grain imports were

    imposed by the British government after

    the Napoleonic wars

    Economists debated the effects of these

    corn laws between 1829 and 1845

    what effect would the elimination of these

    tariffs have on factor prices?

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    37

    The Corn Laws Debate

    Quantity of Grain (x)

    Quantity ofmanufactured

    goods (y)

    U1

    U2

    x0

    If the corn laws completely prevented

    trade, output would bex0and y0

    y0

    The equilibrium prices will be

    px* andpy*

    *

    *slope

    y

    x

    p

    p

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    38

    The Corn Laws Debate

    Quantity of Grain (x)

    Quantity ofmanufactured

    goods (y)

    x0

    U1

    U2

    y0

    Removal of the corn laws will change

    the prices topx andpy

    '

    'slope

    y

    x

    p

    p

    Output will bex1 and y1

    x1

    y1

    y1

    x1

    Individuals will demandx1and y1

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    39

    The Corn Laws Debate

    Quantity of Grain (x)

    Quantity ofmanufactured

    goods (y)

    y1

    x0

    U1

    U2

    x1

    y0

    '

    'slope

    y

    x

    p

    p

    x1

    y1

    Grain imports will bex1x1

    imports of grain

    These imports will be financed by

    the export of manufactured goods

    equal to y1 y1exportsof

    goods

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    40

    The Corn Laws Debate

    We can use an Edgeworth box diagram

    to see the effects of tariff reduction on

    the use of labor and capital If the corn laws were repealed, there

    would be an increase in the production

    of manufactured goods and a decline in

    the production of grain

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    41

    The Corn Laws Debate

    Ox

    Oy

    Total Labor

    TotalCapital

    A repeal of the corn laws would result in a movement fromp3to

    p1where more yand lessxis produced

    x2x1

    x4

    x3

    y1

    y2

    y3

    y4

    p4

    p3

    p2

    p1

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    42

    The Corn Laws Debate

    If we assume that grain production is

    relatively capital intensive, the movement

    fromp3top1causes the ratio of ktoltorise in both industries

    the relative price of capital will fall

    the relative price of labor will rise

    The repeal of the corn laws will be

    harmful to capital owners and helpful to

    laborers

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    43

    Political Support for

    Trade Policies Trade policies may affect the relative

    incomes of various factors of production

    In the United States, exports tend to beintensive in their use of skilled labor

    whereas imports tend to be intensive in

    their use of unskilled labor free trade policies will result in rising relative

    wages for skilled workers and in falling

    relative wages for unskilled workers

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    44

    Existence of General

    Equilibrium Prices Beginning with 19th century investigations

    by Leon Walras, economists have

    examined whether there exists a set ofprices that equilibrates all markets

    simultaneously

    if this set of prices exists, how can it befound?

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    45

    Existence of General

    Equilibrium Prices Suppose that there are ngoods in fixed

    supply in this economy

    let Si(i=1,,n) be the total supply of good iavailable

    letpi(i=1,n) be the price of good i

    The total demand for good idepends onall prices

    Di (p1,,pn) for i=1,,n

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    46

    Existence of General

    Equilibrium Prices We will write this demand function as

    dependent on the whole set of prices (P)

    Di (P)

    Walras problem: Does there exist an

    equilibrium set of prices such that

    Di (P*) = Si

    for all values of i?

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    47

    Excess Demand Functions

    The excess demand function for any

    good iat any set of prices (P) is defined

    to beEDi (P) = Di (P)Si

    This means that the equilibrium

    condition can be rewritten asEDi (P*) = Di (P*)Si= 0

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    48

    Excess Demand Functions

    Demand functions are homogeneous of

    degree zero

    this implies that we can only establishequilibrium relative prices in a Walrasian-

    type model

    Walras also assumed that demand

    functions are continuous

    small changes in price lead to small changes

    in quantity demanded

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    49

    Walras Law

    A final observation that Walras made

    was that the nexcess demand equations

    are not independent of one another Walras lawshows that the total value of

    excess demand is zero at any set of

    prices

    n

    i

    ii PEDP1

    0)(

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    50

    Walras Law

    Walras law holds for any set of prices

    (not just equilibrium prices)

    There can be neither excess demand forall goods together nor excess supply

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    51

    Walras Proof of the Existence

    of Equilibrium Prices The market equilibrium conditions

    provide (n-1) independent equations in

    (n-1) unknown relative prices can we solve the system for an equilibrium

    condition?

    the equations are not necessarily linear all prices must be nonnegative

    To attack these difficulties, Walras set up

    a complicated proof

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    52

    Walras Proof of the Existence

    of Equilibrium Prices Start with an arbitrary set of prices

    Holding the other n-1 prices constant,

    find the equilibrium price for good 1 (p1)

    Holdingp1 and the other n-2 prices

    constant, solve for the equilibrium price

    of good 2 (p2) in changingp2from its initial position top2,

    the price calculated for good 1 does not

    need to remain an equilibrium price

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    54

    Walras Proof of the Existence

    of Equilibrium Prices The importance of Walras proof is its

    ability to demonstrate the simultaneous

    nature of the problem of findingequilibrium prices

    Because it is cumbersome, it is not

    generally used today More recent work uses some relatively

    simple tools from advanced mathematics

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    58

    Brouwers Fixed-Point Theorem

    A mapping is continuous if points that are

    close to each other are mapped into other

    points that are close to each other The Brouwer fixed-point theorem considers

    mappings defined on certain kinds of sets

    closed (they contain their boundaries)

    bounded (none of their dimensions is infinitely

    large)

    convex (they have no holes in them)

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    60

    Proof of the Existence of

    Equilibrium Prices These new prices will retain their original

    relative values and will sum to 1

    1'1

    n

    i

    ip

    j

    i

    j

    i

    p

    p

    p

    p

    '

    '

    These new prices will sum to 1

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    61

    Proof of the Existence of

    Equilibrium Prices We will assume that the feasible set of

    prices (S) is composed of all

    nonnegative numbers that sum to 1 Sis the set to which we will apply Brouwers

    theorem

    Sis closed, bounded, and convex we will need to define a continuous mapping

    of Sinto itself

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    62

    Free Goods

    Equilibrium does not really require that

    excess demand be zero for every market

    Goods may exist for which the marketsare in equilibrium where supply exceeds

    demand (negative excess demand)

    it is necessary for the prices of these goods

    to be equal to zero

    free goods

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    64

    Mapping the Set of Prices

    Into Itself In order to achieve equilibrium, prices of

    goods in excess demand should be

    raised, whereas those in excess supply

    should have their prices lowered

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    65

    Mapping the Set of Prices

    Into Itself We define the mapping F(P) for any

    normalized set of prices (P), such that

    the ith component of F(P) is given by

    Fi(P) =pi+ EDi (P)

    The mapping performs the necessary

    task of appropriately raising or lowering

    prices

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    66

    Mapping the Set of Prices

    Into Itself Two problems exist with this mapping

    First, nothing ensures that the prices will

    be nonnegative the mapping must be redefined to be

    Fi(P) = Max [pi+ EDi (P),0]

    the new prices defined by the mapping must

    be positive or zero

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    67

    Mapping the Set of Prices

    Into Itself Second, the recalculated prices are not

    necessarily normalized

    they will not sum to 1

    it will be simple to normalize such that

    n

    i

    i PF1

    1)(

    we will assume that this normalization has

    been done

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    68

    Application of Brouwers

    Theorem Thus, Fsatisfies the conditions of the

    Brouwer fixed-point theorem

    it is a continuous mapping of the set Sintoitself

    There exists a point (P*) that is mapped

    into itself For this point,

    pi* = Max [pi* + EDi (P*),0] for all i

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    69

    Application of Brouwers

    Theorem This says that P* is an equilibrium set of

    prices

    forpi* > 0,pi* =pi* + EDi (P*)

    EDi (P*) = 0

    Forpi* = 0,

    pi* + EDi (P*) 0

    EDi (P*) 0

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    70

    A General Equilibrium with

    Three Goods The economy of Oz is composed only of

    three precious metals: (1) silver, (2)

    gold, and (3) platinum there are 10 (thousand) ounces of each

    metal available

    The demands for gold and platinum are

    1121

    3

    1

    22

    p

    p

    p

    pD 182

    1

    3

    1

    23

    p

    p

    p

    pD

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    71

    A General Equilibrium with

    Three Goods Equilibrium in the gold and platinum

    markets requires that demand equal

    supply in both markets simultaneously

    101121

    3

    1

    2 p

    p

    p

    p

    101821

    3

    1

    2 p

    p

    p

    p

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    72

    A General Equilibrium with

    Three Goods This system of simultaneous equations

    can be solved as

    p2/p1= 2 p3/p1= 3

    In equilibrium:

    gold will have a price twice that of silver

    platinum will have a price three times thatof silver

    the price of platinum will be 1.5 times thatof gold

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    74

    Smiths Invisible Hand

    Hypothesis Adam Smith believed that the

    competitive market system provided a

    powerful invisible hand that ensuredresources would find their way to where

    they were most valued

    Reliance on the economic self-interestof individuals and firms would result in a

    desirable social outcome

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    75

    Smiths Invisible Hand

    Hypothesis Smiths insights gave rise to modern

    welfare economics

    The First Theorem of Welfare

    Economics suggests that there is an

    exact correspondence between the

    efficient allocation of resources and thecompetitive pricing of these resources

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    77

    Efficiency in Production

    An allocation of resources is efficient in

    production (or technically efficient) if no

    further reallocation would permit more of

    one good to be produced without

    necessarily reducing the output of some

    other good

    Technical efficiency is a precondition for

    Pareto efficiency but does not guarantee

    Pareto efficiency

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    78

    Efficient Choice of Inputs for a

    Single Firm A single firm with fixed inputs of labor

    and capital will have allocated these

    resources efficiently if they are fullyemployed and if the RTSbetween

    capital and labor is the same for every

    output the firm produces

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    79

    Efficient Choice of Inputs for a

    Single Firm Assume that the firm produces two

    goods (xand y) and that the available

    levels of capital and labor are kand l The production function forxis given by

    x= f(kx,lx)

    If we assume full employment, theproduction function for yis

    y= g(ky,ly) = g(k-kx,l

    -lx)

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    80

    Efficient Choice of Inputs for a

    Single Firm Technical efficiency requires thatx

    output be as large as possible for any

    value of y(y) Setting up the Lagrangian and solving for

    the first-order conditions:

    L= f

    (kx,lx) + [yg

    (k

    -

    kx,l

    -

    lx)]L/kx= fk+ gk= 0

    L/lx= fl+ gl= 0

    L/= yg

    (k

    -

    kx,l

    -

    lx) = 0

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    81

    Efficient Choice of Inputs for a

    Single Firm From the first two conditions, we can see

    that

    ll gg

    ff kk

    This implies that

    RTSx(kfor l) = RTSy(kfor l)

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    82

    Efficient Allocation of

    Resources among Firms Resources should be allocated to those

    firms where they can be most efficiently

    used

    the marginal physical product of any

    resource in the production of a particular

    good should be the same across all firmsthat produce the good

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    83

    Efficient Allocation of

    Resources among Firms Suppose that there are two firms

    producingxand their production

    functions are

    f1(k1,l1)

    f2(k2,l2)

    Assume that the total supplies of capital

    and labor are kand l

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    84

    Efficient Allocation of

    Resources among Firms The allocational problem is to maximize

    x= f1(k1,l1) + f2(k2,l2)

    subject to the constraintsk1+ k2= k

    l1+ l2= l

    Substituting, the maximization problembecomes

    x= f1(k1,l1) + f2(k-k1,l

    -l1)

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    85

    Efficient Allocation of

    Resources among Firms First-order conditions for a maximum

    are

    02

    2

    1

    1

    1

    2

    1

    1

    1

    k

    f

    k

    f

    k

    f

    k

    f

    k

    x

    02

    2

    1

    1

    1

    2

    1

    1

    1

    lllll

    ffffx

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    86

    Efficient Allocation of

    Resources among Firms These first-order conditions can be

    rewritten as

    2

    2

    1

    1

    k

    f

    k

    f

    2

    2

    1

    1

    ll

    ff

    The marginal physical product of each

    input should be equal across the two

    firms

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    88

    Efficient Choice of Output

    by Firms The Lagrangian for this problem is

    L=x1+x2+ [y* - f1(x1) - f2(x2)]

    and yields the first-order condition:

    f1/x1= f2/x2

    The rate of product transformation

    (RPT) should be the same for all firms

    producing these goods

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    89

    Efficient Choice of Output

    by Firms

    Trucks Trucks

    Cars Cars

    Firm A Firm B

    50 50

    100 1001

    2

    RPT 1

    1RPT

    FirmAis relatively efficient at producing cars, while Firm B

    is relatively efficient at producing trucks

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    91

    Theory of Comparative

    Advantage The theory of comparative advantage

    was first proposed by Ricardo

    countries should specialize in producingthose goods of which they are relatively

    more efficient producers

    these countries should then trade with the rest

    of the world to obtain needed commodities

    if countries do specialize this way, total

    world production will be greater

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    92

    Efficiency in Product Mix

    Technical efficiency is not a sufficient

    condition for Pareto efficiency

    demand must also be brought into thepicture

    In order to ensure Pareto efficiency, we

    must be able to tie individualspreferences and production possibilities

    together

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    93

    Efficiency in Product Mix

    The condition necessary to ensure that

    the right goods are produced is

    MRS= RPT the psychological rate of trade-off between

    the two goods in peoples preferences must

    be equal to the rate at which they can be

    traded off in production

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    94

    Efficiency in Product Mix

    Output ofx

    Output of y Suppose that we have a one-person (Robinson

    Crusoe) economy and PPrepresents the

    combinations ofxand ythat can be produced

    P

    P

    Any point on PPrepresents a

    point of technical efficiency

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    96

    Efficiency in Product Mix

    Assume that there are only two goods

    (xand y) and one individual in society

    (Robinson Crusoe) Crusoes utility function is

    U= U(x,y)

    The production possibility frontier is

    T(x,y) = 0

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    97

    Efficiency in Product Mix

    Crusoes problem is to maximize his

    utility subject to the production

    constraint

    Setting up the Lagrangian yields

    L= U(x,y) +

    [T(x,y)]

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    98

    Efficiency in Product Mix

    First-order conditions for an interior

    maximum are

    0

    xT

    xU

    xL

    0

    y

    T

    y

    U

    y

    L

    0),(

    yxT

    L

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    99

    Efficiency in Product Mix

    Combining the first two, we get

    yT

    xT

    yU

    xU

    /

    /

    /

    /

    or

    )for()(along)for( yxRPTTdxdyyxMRS

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    102

    Efficiency in Production

    In minimizing costs, a firm will equate

    the RTSbetween any two inputs (kand

    l) to the ratio of their competitive prices(w/v)

    this is true for all outputs the firm produces

    RTSwill be equal across all outputs

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    103

    Efficiency in Production

    A profit-maximizing firm will hire

    additional units of an input (l) up to the

    point at which its marginal contributionto revenues is equal to the marginal

    cost of hiring the input (w)

    pxfl= w

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    104

    Efficiency in Production

    If this is true for every firm, then with a

    competitive labor market

    pxfl1

    = w=pxfl2

    fl1= f

    l2

    Every firm that producesxhas identical

    marginal productivities of every input inthe production ofx

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    105

    Efficiency in Production

    Recall that the RPT(ofxfor y) is equal

    to MCx /MCy

    In perfect competition, each profit-maximizing firm will produce the output

    level for which marginal cost is equal to

    price

    Sincepx= MCxandpy= MCyfor every

    firm, RTS= MCx /MCy=px/py

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    106

    Efficiency in Production

    Thus, the profit-maximizing decisions

    of many firms can achieve technical

    efficiency in production without any

    central direction

    Competitive market prices act as

    signals to unify the multitude of

    decisions that firms make into one

    coherent, efficient pattern

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    107

    Efficiency in Product Mix

    The price ratios quoted to consumers

    are the same ratios the market presents

    to firms

    This implies that the MRSshared by all

    individuals will be equal to the RPT

    shared by all the firms

    An efficient mix of goods will therefore

    be produced

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    108

    Efficiency in Product Mix

    Output ofx

    Output of y

    P

    P

    U0

    x* and y* represent the efficient output mix

    x*

    y*

    Only with a price ratio of

    px*/py* will supply and

    demand be in equilibrium

    *

    *slope

    y

    x

    p

    p

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    109

    Laissez-Faire Policies

    The correspondence between

    competitive equilibrium and Pareto

    efficiency provides some support for the

    laissez-faire position taken by many

    economists

    government intervention may only result in

    a loss of Pareto efficiency

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    112

    Externalities

    An externality occurs when there are

    interactions among firms and individuals

    that are not adequately reflected in

    market prices With externalities, market prices no

    longer reflect all of a goods costs of

    production there is a divergence between private and

    social marginal cost

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    113

    Public Goods

    Public goods have two properties that

    make them unsuitable for production in

    markets

    they are nonrival

    additional people can consume the benefits of

    these goods at zero cost

    they are nonexclusive extra individuals cannot be precluded from

    consuming the good

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    114

    Imperfect Information

    If economic actors are uncertain about

    prices or if markets cannot reach

    equilibrium, there is no reason to expect

    that the efficiency property ofcompetitive pricing will be retained

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    115

    Distribution

    Although the First Theorem of Welfare

    Economics ensures that competitive

    markets will achieve efficient allocations,

    there are no guarantees that these

    allocations will exhibit desirable

    distributions of welfare among individuals

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    117

    DistributionO

    J

    OS

    Total Y

    Total X

    UJ4

    UJ3

    UJ2

    UJ1

    US4

    US3

    US2

    US1

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    119

    DistributionO

    J

    OS

    UJ4

    UJ3

    UJ2

    UJ1

    US4

    US3

    US2

    US1

    A

    Any trade in this area is

    an improvement over A

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    120

    Contract Curve

    In an exchange economy, all efficient

    allocations lie along a contract curve

    points off the curve are necessarily

    inefficient individuals can be made better off by moving to

    the curve

    Along the contract curve, individualspreferences are rivals

    one may be made better off only by making

    the other worse off

    C C

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    121

    Contract CurveO

    J

    OS

    UJ4

    UJ3

    UJ2

    UJ1

    US4

    US3

    US2

    US1

    A

    Contract curve

    Exchange with Initial

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    122

    Exchange with Initial

    Endowments Suppose that the two individuals

    possess different quantities of the two

    goods at the start it is possible that the two individuals could

    both benefit from trade if the initial

    allocations were inefficient

    Exchange with Initial

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    123

    Exchange with Initial

    Endowments Neither person would engage in a trade

    that would leave him worse off

    Only a portion of the contract curveshows allocations that may result from

    voluntary exchange

    Exchange with Initial

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    124

    Exchange with Initial

    Endowments OJ

    OS

    UJA

    USA

    A

    Suppose thatArepresents

    the initial endowments

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    Exchange with Initial

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    126

    Exchange with Initial

    Endowments OJ

    OS

    UJA

    USA

    A

    Only allocations between M1

    and M2will be acceptable to

    both

    M1

    M2

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    127

    The Distributional Dilemma

    If the initial endowments are skewed in

    favor of some economic actors, the

    Pareto efficient allocations promised by

    the competitive price system will also

    tend to favor those actors

    voluntary transactions cannot overcome

    large differences in initial endowments

    some sort of transfers will be needed to

    attain more equal results

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    128

    The Distributional Dilemma

    These thoughts lead to the Second

    Theorem of Welfare Economics

    any desired distribution of welfare among

    individuals in an economy can be achieved

    in an efficient manner through competitive

    pricing if initial endowments are adjusted

    appropriately

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    129

    Important Points to Note:

    Preferences and production

    technologies provide the building

    blocks upon which all general

    equilibrium models are based

    one particularly simple version of such a

    model uses individual preferences for two

    goods together with a concave productionpossibility frontier for those two goods

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    130

    Important Points to Note:

    Competitive markets can establish

    equilibrium prices by making marginal

    adjustments in prices in response to

    information about the demand and

    supply for individual goods

    Walras law ties markets together so that

    such a solution is assured (in most cases)

    I P i N

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    131

    Important Points to Note:

    Competitive prices will result in a

    Pareto-efficient allocation of resources

    this is the First Theorem of Welfare

    Economics

    I t t P i t t N t

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    132

    Important Points to Note:

    Factors that will interfere with

    competitive markets abilities to

    achieve efficiency include

    market power

    externalities

    existence of public goods

    imperfect information

    I t t P i t t N t

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    Important Points to Note:

    Competitive markets need not yield

    equitable distributions of resources,

    especially when initial endowments are

    very skewed

    in theory any desired distribution can be

    attained through competitive markets

    accompanied by lump-sum transfers there are many practical problems in


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