竞争性市场资料课件

©

2007Thomson

South-WesternWHAT

IS

A

COMPETITIVE

MARKET?什么是竞争性市场?©

2007Thomson

South-WesternA

competitive

market

has

many

buyers

andsellers

trading

identical

products

so

thateach

buyer

and

seller

is

a

price

taker.竞争性市场拥有许多买者和卖者,他们所交易的是相同的产品,因此每一个买者和卖者都是价格的接受者.Buyers

and

sellers

must

accept

the

price

determined

bythe

market.买者和卖者必须接受市场决定的价格.The

Meaning

of

Competition竞争的涵义A

perfectly

competitive

market

has

the

followingcharacteristics:一个完全竞争的市场具有下列特征:There

are

many

buyers

and

sellers

in

the

market.市场上存在着许多买者和卖者The

goods

offered

by

the

various

sellers

are

largely

thesame.由各个不同的卖者所提供的商品在很大程度上是相同的。Firms

can

freely

enter

or

exit

themarket.企业能够自由地进入和退出市场。©

2007Thomson

South-WesternThe

Meaning

of

Competition竞争的涵义As

a

result

of

its

characteristics,

the

perfectly

competitivemarket

has

the

following

outcomes:作为其特征的结果，完全竞争市场具有下列结果：The

actions

of

any

single

buyer

or

seller

in

the

market

have

anegligible

impact

on

the

marketprice.市场上任何单一的买者或卖者对市场价格的影响都是微不足道的。Each

buyer

and

seller

takes

the

market

price

asgiven.每一个买者或卖者把市场价格都看作是给定的。©

2007Thomson

South-WesternThe

Revenue

of

a

CompetitiveFirm竞争性企业的收益Total

revenue

for

a

firm

is

the

selling

pricetimes

the

quantitysold.企业的总收益是销售价格乘出售的数量TR

=

(P

×

Q)Total

revenue

is

proportional

to

the

amountofoutput.总收益与产出数量成比例©

2007Thomson

South-WesternThe

Revenue

of

a

CompetitiveFirm竞争性企业的收益Average

revenue

tells

us

how

much

revenue

afirm

receives

for

the

typical

unitsold.平均收益告诉我们一个企业从销售的典型单位中获取多少收益Average

revenue

is

total

revenue

divided

bythe

quantity

sold.平均收益是总收益除销售数量©

2007Thomson

South-WesternThe

Revenue

of

a

CompetitiveFirm竞争性企业的收益In

perfect

competition,

average

revenue

equals

the

price

ofthe

good.在完全竞争中，平均收益等于商品的价格。©

2007Thomson

South-WesternThe

Revenue

of

a

CompetitiveFirm竞争性企业的收益Marginal

revenueis

the

change

intotalrevenue

from

an

additional

unitsold.边际收益是来自新增一单位销售的总收益变化MR

=ΔTR/ΔQFor

competitive

firms,

marginal

revenueequals

the

price

of

thegood.对于竞争性企业来说，边际收益等于商品的价格。©

2007Thomson

South-WesternTable

1 Total,

Average,

and

Marginal

Revenue

for

aCompetitive

Firm©

2007Thomson

South-WesternPROFIT

MAXIMIZATION

AND

THE

COMPETITIVEFIRM’S

SUPPLY

CURVE©

2007Thomson

South-Western利润最大化与竞争性企业的供给曲线The

goal

of

a

competitive

firm

is

tomaximize

profit.竞争性企业的目标是使利润达到最大化This

means

that

the

firm

will

want

toproduce

the

quantity

that

maximizes

thedifference

between

total

revenue

and

totalcost.这意味着企业想要生产的数量能够使得总收益与总成本之间的差额达到最大化。Table

2 Profit

Maximization:

A

Numerical

Example表2：利润最大化---一个数字化范例©

2007Thomson

South-Western©

2007Thomson

South-WesternThe

Marginal

Cost-Curve

and

the

Firm’s

SupplyDecision边际成本曲线与企业的供给决策Profit

maximization

occurs

at

the

quantity

where

marginalrevenue

equals

marginal

cost.利润最大化出现在边际收益等于边际成本的数量上。When

MR>MC,increase

Q

当边际收益大于边际成本时，数量增加。When

MR<MC, decrease

Q当边际收益小于边际成本时，数量减少。When

MR

=

MC,

profit

is

maximized.当边际收益等于边际成本时，利润达到最大化。Figure

1

Profit

Maximization

for

a

Competitive

Firm图1：竞争性企业的利润最大化Quantity0CostsandRevenueMCAVCMC1Q1MC2Q2The

firm

maximizesprofit

by

producingthe

quantity

at

whichmarginal

cost

equalsmarginal

revenue.QMAXP

=

MR1

=

MR2ATCP

=

AR

=

MRIf

the

firmproduces

Q1,marginal

cost

isMC1.If

the

firm

producesQ2,

marginal

cost

isMC2.Suppose

the

market

price

is

P.©

2007Thomson

South-WesternFigure

2

Marginal

Cost

as

the

Competitive

Firm’s

SupplyCurve图2：作为竞争性企业供给曲线的边际成本Quantity0PriceMCATCAVCP1Q1P2Q2So,

this

section

of

thefirm’s

MC

curve

isalso

the

firm’s

supplycurve.As

P

increases,

the

firmwill©

2007Thomson

South-Westernselect

its

level

ofoutputalong

the

MC

curve.The

Firm’s

Short-Run

Decision

to

Shut

Down企业关闭的短期决策A

shutdown

refers

to

ashort-run

decision

notto

produce

anything

during

a

specific

periodof

time

because

of

current

marketconditions.暂时关闭是指在某一特定时期内因为当时的市场条件而决定不生产任何东西的短期决策Exit

refers

to

a

long-run

decision

to

leave

themarket.退出是指离开市场的长期决策©

2007Thomson

South-WesternThe

Firm’s

Short-Run

Decision

to

Shut

Down企业关闭的短期决策The

firm

shuts

down

if

the

revenue

it

getsfrom

producing

is

less

than

the

variable

costofproduction.如果来自其生产的收益小于生产成本时，企业会暂时关闭。Shut

down

if

TR

<

VCShut

down

if

TR/Q

<

VC/QShut

down

if

P

<

AVC©

2007Thomson

South-WesternFigure

3

The

Competitive

Firm’sShort-Run

Supply

Curve图3：竞争性企业的短期供给曲线MCQuantityATCAVC0CostsFirmshutsdown

ifP

<

AVCFirm’s

short-runsupply

curveIf

P

>

AVC,

firm

willcontinue

to

producein

the

short

run.If

P

>

ATC,

the

firmwill

continue

to©

2007Thomson

South-Westernproduce

at

a

profit.Spilt

Milk

and

Other

Sunk

CostsThe

firm

considers

its

sunk

costs

whendeciding

to

exit,

but

ignores

them

whendeciding

whether

to

shut

down.在决定退出时企业考虑其沉淀成本，但是在决定是否暂时关闭时可忽略沉淀成本。Sunk

costs

are

costs

that

have

already

beencommitted

and

cannot

berecovered.沉淀成本是已经投入并且无法挽回的成本©

2007Thomson

South-WesternThe

Firm’s

Short-Run

Decision

to

Shut

Down企业关闭的短期决策The

portion

ofthemarginal-costcurvethatlies

above

average

variable

cost

is

thecompetitive

firm’sshort-run

supply

curve.边际成本曲线位于平均可变成本以上的部分是竞争性企业的短期供给曲线。©

2007Thomson

South-WesternThe

Firm’s

Long-Run

Decision

to

Exit

or

Enter

aMarket企业退出或者进入一个市场的长期决策In

the

long

run,

the

firm

exits

if

therevenueit

would

get

from

producing

is

less

than

itstotal

cost.在长期中，如果企业从生产中获得的收益小于其总成本的话，它就退出。Exit

if

TR

<

TCExit

if

TR/Q

<

TC/QExit

if

P

<

ATC©

2007Thomson

South-WesternThe

Firm’s

Long-Run

Decision

to

Exit

or

Enter

aMarket企业退出或者进入一个市场的长期决策A

firm

will

enter

the

industry

if

such

anaction

would

be

profitable.如果此类行为有利可图的话，企业将进入该行业。Enter

if

TR

>

TCEnter

if

TR/Q

>

TC/QEnter

if

P

>

ATC©

2007Thomson

South-WesternFigure

4

The

Competitive

Firm’s

Long-Run

Supply

Curve图4：竞争性市场的长期供给曲线MC

=

long-run

SFirmexitsifP<

ATCQuantityATC0CostsFirm’s

long-runsupply

curveFirmenters

ifP>

ATC©

2007Thomson

South-WesternMeasuring

Profit

in

Our

Graph

for

the

CompetitiveFirm在我们有关竞争性企业的图中测度利润Profit

=

TR

–

TCProfit

=

(TR/Q

–TC/Q)

xQProfit

=

(P–

ATC)xQ©

2007Thomson

South-Western©

2007Thomson

South-WesternFigure

5

Profit

as

the

Area

between

Price

and

Average

Total

Cost图5：价格与平均总成本之间的面积是利润(a)

A

Firm

withProfits有利润的企业Quantity0PriceP

=

AR

=

MRATCMCATCQ(profit-maximizing

quantity)利润最大化数量ProfitP©

2007Thomson

South-WesternFigure

5

Loss

as

the

Area

between

Average

Total

Cost

and

Price图5：平均总成本与价格之间的面积是亏损(b)

A

Firm

withLosses有亏损的企业Quantity0PriceMC

ATC(loss-minimizing

quantity)亏损最小数量P

=

AR

=

MRATCPQLossTHE

SUPPLY

CURVE

IN

A

COMPETITIVE

MARKET©

2007Thomson

South-Western竞争性市场中的供给曲线The

competitive

firm’s

long-runsupplycurve

is

theportionofits

marginal-costcurve

that

lies

above

average

totalcost.竞争性企业的长期供给曲线是位于平均总成本曲线之上的边际成本曲线。THE

SUPPLY

CURVE

IN

A

COMPETITIVE

MARKET©

2007Thomson

South-Western竞争性市场中的供给曲线Short-Run

Supply

Curve

短期供给曲线The

portion

of

its

marginal

cost

curve

that

lies

aboveaverage

variable

cost.

边际成本曲线位于平均可变成本之上的部分Long-RunSupplyCurve

长期供给曲线The

marginal

cost

curve

above

the

minimum

point

of

itsaverage

total

cost

curve.边际成本曲线位于其平均总成本曲线的最低点之上THE

SUPPLY

CURVE

IN

A

COMPETITIVE

MARKET©

2007Thomson

South-Western竞争性市场中的供给曲线Market

supply

equals

the

sum

of

thequantities

supplied

by

the

individual

firmsin

the

market.市场供给等于市场中个别企业所供给的数量之总和©

2007Thomson

South-WesternThe

Short

Run:

Market

Supply

with

a

Fixed

Number

ofFirms短期：企业数量固定的市场供给For

any

given

price,

each

firm

supplies

aquantity

of

output

so

that

its

marginal

costequals

price.对于任何给定的价格，每一企业供给特定的产出数量。以便使其边际成本等于价格。The

market

supply

curve

reflects

theindividual

firms’

marginal

cost

curves.市场供给曲线反映出个别企业的边际成本曲线Figure

6

Short-RunMarket

Supply图6：短期市场供给(a)

Individual

Firm

Supply个别企业的供给Quantity

(firm)0PriceMC1.00100$2.00200(b)

Market

Supply市场供给Quantity

(market)0PriceSupply1.00100,000$2.00200,000If

the

industry

has

1000

identical

firms,

then

at

each

market

price,

industry

output

will

be1000

times

larger

than

the

representative

firm’s

output.如果该产业拥有一千家相同企业，该产业的产出将比代表性企业的产出大一千倍。©

2007Thomson

South-WesternThe

Long

Run:

Market

Supply

with

Entry

and

Exit长期：有进入与退出的市场供给Firms

will

enter

or

exit

the

marketuntilprofit

is

driven

to

zero.企业将进入或退出市场直到利润趋向于零In

the

long

run,

price

equals

the

minimum

ofaverage

totalcost.在长期中，价格等于平均总成本的最低点。The

long-run

market

supply

curve

ishorizontal

at

this

price.长期市场供给曲线在此价格呈水平状©

2007Thomson

South-WesternFigure

7

Long-Run

Market

Supply图7：长期市场供给(a)

Firm’s

Zero-Profit

ConditionQuantity

(firm)0Price(b)

Market

SupplyQuantity

(market)Price0P

=

minimumATCSupply©

2007Thomson

South-WesternMCATCThe

Long

Run:

Market

Supply

with

Entry

and

Exit长期：有进入与退出的市场供给At

the

end

of

the

process

of

entry

and

exit,

firms

that

remainmust

be

making

zero

economicprofit.在进入和退出过程结束时，留存的企业必定获得零经济利润。The

process

of

entry

and

exit

ends

only

when

price

andaverage

total

cost

are

driven

to

equality.只有在价格与平均总成本趋向相等时，进入和退出过程才会结束。Long-run

equilibrium

must

have

firms

operating

at

theirefficient

scale.长期均衡必定使得企业在其有效规模水平上运行©

2007Thomson

South-WesternWhy

Do

Competitive

Firms

Stay

in

Business

If

They

Make

ZeroProfit?为什么竞争性企业在获得零利润时还要留存在其业务之中？Profit

equals

total

revenue

minus

total

cost.利润等于总收益减去总成本Total

cost

includes

all

the

opportunitycostsofthe

firm.总成本包括企业的所有机会成本In

thezero-profit

equilibrium,

thefirm’srevenue

compensates

the

owners

for

the

timeand

money

they

expend

to

keep

thebusinessgoing.在零利润均衡中，企业的收益补偿了©所2007

Th有omson

S者outh-WesternA

Shift

in

Demand

in

the

Short

Run

and

Long

Run短期与长期中的需求变动An

increase

in

demand

raises

price

andquantity

in

the

short

run.在短期内，需求增加会提高价格和数量。Firms

earn

profits

because

price

now

exceedsaverage

totalcost.企业获得利润，因为目前价格超越了总成本。©

2007Thomson

South-WesternFigure

8

An

Increase

in

Demand

in

the

Short

Run

and

Long

Run图8：短期与长期中的需求增加Firm(a)

Initial

Condition初始条件Quantity

(firm)0PriceMarketQuantity

(market)Price0Demand,

D1Short-run

supply,

S1P1ATCLong-runsupplyP1Q1AMCA

market

begins

in

long

runequilibrium.在长期均衡中市场启动©

2007Thomson

South-WesternAnd

firms

earn

zero

profit.企业获得零利润Figure

8

An

Increase

in

Demand

in

the

Short

Run

and

Long

RunMarketFirm(b)Short-Run

Response短期反应Quantity

(firm)0PriceP1Quantity

(market)Long-runsupplyPrice0D2D1P1S1P2AQ1

Q2P2BATCMC©

2007Thomson

South-Western图8：短期和长期中的需求增加An

increase

in

market

demand……raises

price

and

output.The

higher

P

encourages

firms

to

producemore…

…andgeneratesshort-runprofit.Figure

8

An

Increase

in

Demand

in

the

Short

Run

and

Long

Run图8：短期与长期中的需求增加长期反应0

Quantity

(firm)PriceMCATCFirm

MarketQuantity

(market)Price0P1P2P1supplyBD2D1S1AS2Long-runQ1

Q2

Q3CProfits

induce

entry

and

market

supply

increases.利润引致进入和市场供给增加(c)

Long-Run

ResponseThe

increase

in

supply

lowers

market

price.供给增加减低市场价格In

the

long

runmarketprice

is

restored,

butmarket

supply

is

greater.©

2007Thomson

South-WesternWhy

the

Long-Run

Supply

Curve

Might

Slope

Upward为什么长期供给曲线会向上倾斜？Some

resources

used

in

production

may

beavailable

only

in

limited

quantities.生产中使用的某些资源也许只能以有限的数量获得Firms

may

have

different

costs.企业也许具有不同的成本Marginal

Firm

边际企业The

marginal

firm

is

the

firm

that

would

exit

themarket

if

the

price

were

any

lower.边际企业是在价格降低时会退出市场的企业©

2007Thomson

South-WesternSummaryBecause

a

competitive

firm

is

a

price

taker,its

revenue

is

proportional

to

the

amount

ofoutput

itproduces.因为竞争性企业是价格接受者，它的收益是与其生产的数量成比例的。The

price

of

the

good

equals

both

thefirm’saverage

revenue

and