market equilibrium. economies work. use most often. · Modern microeconomics is about supply,...

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4The M

ark

et F

orc

es o

f Supply

and D

em

and

•S

upply

and d

em

and a

re th

e tw

o w

ord

s th

at e

conom

ists

use m

ost o

ften.

•S

upply

and d

em

and a

re th

e fo

rces th

at m

ake m

ark

et

econom

ies w

ork

.

•M

odern

mic

roeconom

ics is

about s

upply, d

em

and, a

nd

mark

et e

quilib

rium

.

MA

RK

ET

S A

ND

CO

MP

ET

ITIO

N

•A

mark

et

is a

gro

up o

f buyers

and s

elle

rs o

f a p

artic

ula

r good o

r serv

ice.

•T

he te

rms s

upply

and d

em

and re

fer to

the b

ehavio

r of

people

. . . as th

ey in

tera

ct w

ith o

ne a

noth

er in

mark

ets

.

MA

RK

ET

S A

ND

CO

MP

ET

ITIO

N

•B

uyers

dete

rmin

e d

em

and.

•S

elle

rs d

ete

rmin

e s

upply

Com

petitive

Marke

ts

•A

com

petitiv

em

ark

et

is a

mark

et in

whic

h th

ere

are

many

buyers

and s

elle

rs s

o th

at e

ach h

as a

neglig

ible

impact o

n

the m

ark

et p

rice.

Com

petitio

n: P

erfe

ct and O

therw

ise

•P

erfe

ct C

om

petitio

n•

Pro

du

cts

are

the

sa

me

•N

um

ero

us b

uye

rs a

nd

se

llers

so

tha

t ea

ch

ha

s n

o in

flue

nce

ove

r p

rice

•B

uye

rs a

nd

Se

llers

are

pric

e ta

ke

rs

•M

onopoly

•O

ne

se

ller, a

nd

se

ller c

on

trols

pric

e

Com

petitio

n: P

erfe

ct and O

therw

ise

•O

ligopoly

•F

ew

se

llers

•N

ot a

lwa

ys a

gg

ressiv

e c

om

pe

tition

•M

onopolis

tic C

om

petitio

n

•M

an

y s

elle

rs

•S

ligh

tly d

iffere

ntia

ted

pro

du

cts

•E

ach

se

ller m

ay s

et p

rice

for its

ow

n p

rod

uct

DE

MA

ND

•Q

uantity

dem

anded

is th

e a

mount o

f a g

ood th

at b

uyers

are

willin

g a

nd a

ble

to p

urc

hase.

•Law

of D

em

and

•T

he

law

of d

em

an

dsta

tes th

at, o

the

r thin

gs e

qu

al, th

e q

ua

ntity

d

em

an

de

d o

f a g

oo

d fa

lls w

he

n th

e p

rice

of th

e g

oo

d ris

es.

The D

em

and C

urve

: The R

ela

tionsh

ip b

etw

een P

rice

and Q

uantity D

em

anded

•D

em

and S

chedule

•T

he

de

ma

nd

sch

ed

ule

is a

tab

le th

at s

ho

ws th

e re

latio

nsh

ip

be

twe

en

the

pric

e o

f the

go

od

an

d th

e q

ua

ntity

de

ma

nd

ed

.

Cath

erin

e’s D

em

and S

chedule

The D

em

and C

urve

: The R

ela

tionsh

ip b

etw

een P

rice

and Q

uantity D

em

anded

•D

em

and C

urv

e

•T

he

de

ma

nd

cu

rve

is a

gra

ph

of th

e re

latio

nsh

ip b

etw

ee

n th

e p

rice

of a

go

od

an

d th

e q

ua

ntity

de

ma

nd

ed

.

Fig

ure

1 C

ath

erin

e’s D

em

and S

chedule

and D

em

and C

urve

Co

pyrig

ht ©

2004 S

ou

th-W

este

rn

Pric

e o

f

Ice

-Cre

am

Co

ne0

2.5

0

2.0

0

1.5

0

1.0

0

0.5

0

12

34

56

78

91

011

Qu

an

tity o

f

Ice

-Cre

am

Co

ne

s

$3

.00

12

1. A

de

cre

ase

in

pric

e...

2. ...

incre

ase

s q

ua

ntity

of c

on

es d

em

an

de

d.

Marke

t Dem

and ve

rsus In

divid

ual D

em

and

•M

ark

et d

em

and re

fers

to th

e s

um

of a

ll indiv

idua

l dem

ands fo

r a p

artic

ula

r good o

r serv

ice.

•G

raphic

ally, in

div

idual d

em

and c

urv

es a

re s

um

med

horiz

onta

lly to

obta

in th

e m

ark

et d

em

and c

urv

e.

Shifts in

the D

em

and C

urve

•C

hange in

Quantity

Dem

anded

•M

ove

me

nt a

lon

g th

e d

em

an

d c

urv

e.

•C

au

se

d b

y a

ch

an

ge

in th

e p

rice

of th

e p

rod

uct.

0

D

Price of Ic

e-

Cream

Cones

Quantity

of Ic

e-Cream Cones

A ta

x th

at ra

ise

s th

e

pric

e o

f ice

-cre

am

co

ne

s re

su

lts in

a

mo

ve

me

nt a

lon

g th

e

de

ma

nd

cu

rve

.

A

B

8

1.00

$2.00

4

Changes in

Quantity D

em

anded

Shifts in

the D

em

and C

urve

•C

onsum

er in

com

e

•P

rices o

f rela

ted g

oods

•Taste

s

•E

xpecta

tions

•N

um

ber o

f buye

rs

Shifts in

the D

em

and C

urve

•C

hange in

Dem

and

•A

sh

ift in th

e d

em

an

d c

urv

e, e

ithe

r to th

e le

ft or rig

ht.

•C

au

se

d b

y a

ny c

ha

ng

e th

at a

lters

the

qu

an

tity d

em

an

de

d a

t eve

ry

pric

e.

Fig

ure

3 S

hifts in

the D

em

and C

urve

Co

pyrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice-C

ream

Co

ne

Qu

an

tity o

f

Ice-C

ream

Co

nes

Incre

ase

in d

em

and

Decre

ase

in d

em

and

Dem

and c

urv

e, D

3

Dem

and

curv

e, D

1

Dem

and

curv

e, D

2

0

Shifts in

the D

em

and C

urve

•C

onsum

er In

com

e

•A

s in

co

me

incre

ase

s th

e d

em

an

d fo

r a n

orm

al g

oo

dw

ill incre

ase

.

•A

s in

co

me

incre

ase

s th

e d

em

an

d fo

r an

infe

rior g

oo

dw

ill de

cre

ase

.

$3.00

2.50

2.00

1.50

1.00

0.50

21

345

67

8910

12

11

Price of Ic

e-

Cream Cone

Quantity

of

Ice-Cream

Cones

0

Inc

rea

se

in d

em

an

d

An

incre

ase

in

inco

me

...

D1

D2

Consu

mer In

com

eN

orm

al G

ood

$3.00

2.50

2.00

1.50

1.00

0.50

21

345

67

8910

12

11

Pric

e o

f Ice-

Cre

am

Co

ne

Qu

an

tity o

f Ic

e-C

ream

C

on

es

0

De

cre

as

ein

de

ma

nd

An

incre

ase

in

inco

me

...

D1

D2

Consu

mer In

com

eIn

ferio

r Good

Shifts in

the D

em

and C

urve

•P

rices o

f Rela

ted G

oods

•W

he

n a

fall in

the

pric

e o

f on

e g

oo

d re

du

ce

s th

e d

em

an

d fo

r a

no

the

r go

od

, the

two

go

od

s a

re c

alle

d s

ub

stitu

tes.

•W

he

n a

fall in

the

pric

e o

f on

e g

oo

d in

cre

ase

s th

e d

em

an

d fo

r a

no

the

r go

od

, the

two

go

od

s a

re c

alle

d c

om

ple

me

nts

.

Table

1 V

aria

ble

s That In

fluence

Buye

rs

Co

pyrig

ht©

2004 S

ou

th-W

este

rn

SU

PP

LY

•Q

uantity

supplie

dis

the a

mount o

f a g

ood th

at s

elle

rs a

re

willin

g a

nd a

ble

to s

ell.

•Law

of S

upply

•T

he

law

of s

up

ply

sta

tes th

at, o

the

r thin

gs e

qu

al, th

e q

ua

ntity

su

pp

lied

of a

go

od

rise

s w

he

n th

e p

rice

of th

e g

oo

d ris

es.

The S

upply C

urve

: The R

ela

tionsh

ip b

etw

een P

rice

and Q

uantity S

upplie

d

•S

upply

Schedule

•T

he

su

pp

ly s

ch

ed

ule

is a

tab

le th

at s

ho

ws th

e re

latio

nsh

ip b

etw

ee

n

the

pric

e o

f the

go

od

an

d th

e q

ua

ntity

su

pp

lied

.

Ben’s S

upply S

chedule

Su

pp

lied

The S

upply C

urve

: The R

ela

tionsh

ip b

etw

een P

rice

and Q

uantity S

upplie

d

•S

upply

Curv

e

•T

he

su

pp

lycu

rve

is th

e g

rap

h o

f the

rela

tion

sh

ip b

etw

ee

n th

e p

rice

of a

go

od

an

d th

e q

ua

ntity

su

pp

lied

.

Fig

ure

5 B

en’s S

upply S

chedule

and S

upply C

urveC

op

yrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice

-Cre

am

Co

ne

0

2.5

0

2.0

0

1.5

0

1.0

0

12

34

56

78

91

011

Qu

an

tity o

f

Ice

-Cre

am

Co

ne

s

$3

.00

12

0.5

0

1. A

nin

cre

ase

in p

rice

...

2. ...

incre

ase

s q

ua

ntity o

f co

ne

s s

up

plie

d.

Supplie

d

Marke

t Supply ve

rsus In

divid

ual S

upply

•M

ark

et s

upply

refe

rs to

the s

um

of a

ll indiv

idua

l supplie

s

for a

ll selle

rs o

f a p

artic

ula

r good o

r serv

ice.

•G

raphic

ally, in

div

idual s

upply

curv

es a

re s

um

med

horiz

onta

lly to

obta

in th

e m

ark

et s

upply

curv

e.

Shifts in

the S

upply C

urve

•In

put p

rices

•Technolo

gy

•E

xpecta

tions

•N

um

ber o

f selle

rs

Shifts in

the S

upply C

urve

•C

hange in

Quantity

Supplie

d

•M

ove

me

nt a

lon

g th

e s

up

ply

cu

rve

.

•C

au

se

d b

y a

ch

an

ge

in a

nyth

ing

tha

t alte

rs th

e q

ua

ntity

su

pp

lied

at

ea

ch

pric

e.

15

Pric

e o

f Ice-

Cre

am

C

on

e

Qu

an

tity o

f Ic

e-C

ream

C

on

es

0

S

1.00

A

C$3.00

A ris

e in

the p

rice

of ic

e c

ream

cones re

sults

in a

m

ovem

ent a

long

the s

upply

curv

e.

Change in

Quantity S

upplie

d

Shifts in

the S

upply C

urve

•C

hange in

Supply

•A

sh

ift in th

e s

up

ply

cu

rve

, eith

er to

the

left o

r righ

t.

•C

au

se

d b

y a

ch

an

ge

in a

de

term

ina

nt o

the

r tha

n p

rice

.

Fig

ure

7 S

hifts in

the S

upply C

urve

Co

pyrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice

-Cre

am

Co

ne

Qu

an

tity o

f

Ice

-Cre

am

Co

ne

s0

Incre

ase

in s

up

ply

De

cre

ase

in s

up

ply

Su

pp

ly c

urv

e, S

3

cu

rve

, S

up

plyS

1S

up

ply

cu

rve

, S2

Table

2 V

aria

ble

s That In

fluence

Selle

rs

Co

pyrig

ht©

2004 S

ou

th-W

este

rn

SU

PP

LY A

ND

DE

MA

ND

TO

GE

TH

ER

•E

quilib

rium

refe

rs to

a s

ituatio

n in

whic

h th

e p

rice h

as

reached th

e le

vel w

here

quantity

supplie

d e

quals

quantity

dem

anded.

SU

PP

LY A

ND

DE

MA

ND

TO

GE

TH

ER

•E

quilib

rium

Pric

e

•T

he

pric

e th

at b

ala

nce

s q

ua

ntity

su

pp

lied

an

d q

ua

ntity

de

ma

nd

ed

.

•O

n a

gra

ph

, it is th

e p

rice

at w

hic

h th

e s

up

ply

an

d d

em

an

d c

urv

es

inte

rse

ct.

•E

quilib

rium

Quantity

•T

he

qu

an

tity s

up

plie

d a

nd

the

qu

an

tity d

em

an

de

d a

t the

eq

uilib

rium

p

rice

.

•O

n a

gra

ph

it is th

e q

ua

ntity

at w

hic

h th

e s

up

ply

an

d d

em

an

d

cu

rve

s in

ters

ect.

At $

2.0

0, th

e q

uantity

dem

anded

is e

qual to

the q

uantity

supplie

d!

SU

PP

LY A

ND

DE

MA

ND

TO

GE

TH

ER

Demand Schedule

Supply Schedule

Fig

ure

8 T

he E

quilib

rium

of S

upply a

nd D

em

and

Co

pyrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice-C

ream

Co

ne

01

23

45

67

89

10

1112

Qu

an

tity o

f Ice-C

ream

Co

nes

13

Equilib

rium

quantity

Equilib

rium

pric

eE

quilib

rium

Supply

Dem

and

$2.0

0

Fig

ure

9 M

arke

ts Not in

Equilib

rium

Co

pyrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice

-Cre

am

Co

ne

0

Su

pp

ly

De

ma

nd

(a) E

xc

es

s S

up

ply

Qu

an

tity

de

ma

nd

ed

Qu

an

tity

su

pp

lied

Su

rplu

s

Qu

an

tity o

f

Ice

-Cre

am

Co

ne

s

4

$2

.50

10

2.0

0

7

Equilib

rium

•S

urp

lus

•W

he

n p

rice

> e

qu

ilibriu

m p

rice

, the

n q

ua

ntity

su

pp

lied

> q

ua

ntity

d

em

an

de

d.

•T

here

is e

xcess s

upply o

r a s

urp

lus.

•S

upplie

rs w

ill low

er th

e p

rice to

incre

ase s

ale

s, th

ere

by m

ovin

g to

ward

equilib

rium

.

Equilib

rium

•S

horta

ge

•W

he

n p

rice

< e

qu

ilibriu

m p

rice

, the

n q

ua

ntity

de

ma

nd

ed

> th

e

qu

an

tity s

up

plie

d.

•T

here

is e

xcess d

em

and o

r a s

horta

ge.

•S

upplie

rs w

ill rais

e th

e p

rice d

ue to

too m

any b

uye

rs c

hasin

g to

o fe

w

goods, th

ere

by m

ovin

g to

ward

equilib

rium

.

Fig

ure

9 M

arke

ts Not in

Equilib

rium

Co

pyrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice

-Cre

am

Co

ne

0Q

ua

ntity

of

Ice

-Cre

am

Co

ne

s

Su

pp

ly

De

ma

nd

(b) E

xc

es

s D

em

an

d

Qu

an

tity

su

pp

lied

Qu

an

tity

de

ma

nd

ed

1.5

0

10

$2

.00

74

Sh

orta

ge

Equilib

rium

•Law

of s

upply

and d

em

and

•T

he

cla

im th

at th

e p

rice

of a

ny g

oo

d a

dju

sts

to b

ring

the

qu

an

tity

su

pp

lied

an

d th

e q

ua

ntity

de

ma

nd

ed

for th

at g

oo

d in

to b

ala

nce

.

Thre

e S

teps to

Analyzin

g C

hanges in

Equilib

rium

•D

ecid

e w

heth

er th

e e

vent s

hifts

the s

upply

or d

em

and

curv

e (o

r both

).

•D

ecid

e w

heth

er th

e c

urv

e(s

) shift(s

) to th

e le

ft or to

the

right.

•U

se th

e s

upply

-and-d

em

and d

iagra

m to

see h

ow

the s

hift

affe

cts

equilib

rium

pric

e a

nd q

uantity.

Fig

ure

10 H

ow

an In

crease

in D

em

and A

ffects th

e E

quilib

rium

Co

pyrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice

-Cre

am

Co

ne

0Q

ua

ntity

of

Ice

-Cre

am

Co

ne

s

Su

pp

ly

Initia

l

eq

uilib

riumD

D

3.

. . . an

d a

hig

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r

qu

an

tity so

ld.

2. . . . re

su

lting

in a

hig

he

r

pric

e . . .

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ot w

ea

the

r incre

ase

s

the

de

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rea

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qu

ilibriu

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Thre

e S

teps to

Analyzin

g C

hanges in

Equilib

rium

•S

hifts

in C

urv

es v

ers

us M

ovem

ents

alo

ng C

urv

es

•A

sh

ift in th

e s

up

ply

cu

rve

is c

alle

d a

ch

an

ge

in s

up

ply.

•A

mo

ve

me

nt a

lon

g a

fixe

d s

up

ply

cu

rve

is c

alle

d a

ch

an

ge

in

qu

an

tity s

up

plie

d.

•A

sh

ift in th

e d

em

an

d c

urv

e is

ca

lled

a c

ha

ng

e in

de

ma

nd

.

•A

mo

ve

me

nt a

lon

g a

fixe

d d

em

an

d c

urv

e is

ca

lled

a c

ha

ng

e in

q

ua

ntity

de

ma

nd

ed

.

Fig

ure

11 H

ow

a D

ecre

ase

in S

upply A

ffects th

e E

quilib

rium

Co

pyrig

ht©

2003 S

ou

thw

este

rn/T

ho

mso

n L

earn

ing

Pric

e o

f

Ice

-Cre

am

Co

ne

0Q

ua

ntity

of

Ice

-Cre

am

Co

ne

s

De

ma

nd

Ne

we

qu

ilibriu

m

Initia

l eq

uilib

rium

S1

S2

2. . . . re

su

lting

in a

hig

he

rp

rice

of ic

ecre

am

. . .

1. A

n in

cre

ase

in th

ep

rice

of s

ug

ar re

du

ce

sth

e s

up

ply o

f ice

cre

am

. . .

3.. . . a

nd

a lo

we

rq

ua

ntity s

old

.

2.0

0

7

$2

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4

Table

4 W

hat H

appens to

Price

and Q

uantity W

hen S

upply o

r D

em

and S

hifts?

Co

pyrig

ht©

2004 S

ou

th-W

este

rn

Sum

mary

•E

conom

ists

use th

e m

odel o

f supply

and d

em

and to

analy

ze c

om

petitiv

e m

ark

ets

.

•In

a c

om

petitiv

e m

ark

et, th

ere

are

many b

uyers

and

selle

rs, e

ach o

f whom

has little

or n

o in

fluence o

n th

e

mark

et p

rice.

Sum

mary

•T

he d

em

and c

urv

e s

how

s h

ow

the q

uantity

of a

good

depends u

pon th

e p

rice.

•A

cco

rdin

g to

the

law

of d

em

an

d, a

s th

e p

rice

of a

go

od

falls

, the

q

ua

ntity

de

ma

nd

ed

rise

s. T

he

refo

re, th

e d

em

an

d c

urv

e s

lop

es

do

wn

wa

rd.

•In

ad

ditio

n to

pric

e, o

the

r de

term

ina

nts

of h

ow

mu

ch

co

nsu

me

rs

wa

nt to

bu

y in

clu

de

inco

me

, the

pric

es o

f co

mp

lem

en

ts a

nd

su

bstitu

tes, ta

ste

s, e

xp

ecta

tion

s, a

nd

the

nu

mb

er o

f bu

ye

rs.

•If o

ne

of th

ese

facto

rs c

ha

ng

es, th

e d

em

an

d c

urv

e s

hifts

.

Sum

mary

•T

he s

upply

curv

e s

how

s h

ow

the q

uantity

of a

good

supplie

d d

epends u

pon th

e p

rice.

•A

cco

rdin

g to

the

law

of s

up

ply, a

s th

e p

rice

of a

go

od

rise

s, th

e

qu

an

tity s

up

plie

d ris

es. T

he

refo

re, th

e s

up

ply

cu

rve

slo

pe

s u

pw

ard

.

•In

ad

ditio

n to

pric

e, o

the

r de

term

ina

nts

of h

ow

mu

ch

pro

du

ce

rs

wa

nt to

se

ll inclu

de

inp

ut p

rice

s, te

ch

no

log

y, exp

ecta

tion

s, a

nd

the

n

um

be

r of s

elle

rs.

•If o

ne

of th

ese

facto

rs c

ha

ng

es, th

e s

up

ply

cu

rve

sh

ifts.

Sum

mary

•M

ark

et e

quilib

rium

is d

ete

rmin

ed b

y th

e in

ters

ectio

n o

f the

supply

and d

em

and c

urv

es.

•A

t the e

quilib

rium

pric

e, th

e q

uantity

dem

anded e

quals

th

e q

uantity

supplie

d.

•T

he b

ehavio

r of b

uyers

and s

elle

rs n

atu

rally

driv

es

mark

ets

tow

ard

their e

quilib

rium

.

Sum

mary

•To a

naly

ze h

ow

any e

vent in

fluences a

mark

et, w

e u

se

the s

upply

-and-d

em

and d

iagra

m to

exam

ine h

ow

the

even a

ffects

the e

quilib

rium

pric

e a

nd q

uantity.

•In

mark

et e

conom

ies, p

rices a

re th

e s

ignals

that g

uid

e

econom

ic d

ecis

ions a

nd th

ere

by a

llocate

resourc

es.

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