Chapter06

CHAPTE
R 6
Supply, Demand, and
Government Policies
EconomicsMankiw
PRINCIPLES OF

N. Gregory

© 2009 South-Western, a part of Cengage Learning, all rights reserved

In this chapter,
look for the answers to these questions:
 What are price ceilings and price floors?
What are some examples of each?
 How do price ceilings and price floors affect
market outcomes?
 How do taxes affect market outcomes?
How do the effects depend on whether
the tax is imposed on buyers or sellers?
 What is the incidence of a tax?
What determines the incidence?
2

Government Policies That Alter the
Private Market Outcome
 Price controls
 Price ceiling: a legal maximum on the price
of a good or service Example: rent control
 Price floor: a legal minimum on the price of
a good or service Example: minimum wage
 Taxes
 The govt can make buyers or sellers pay a
specific amount on each unit bought/sold.

We will use the supply/demand model to see
We will use the supply/demand model to see
how each policy affects the market outcome
how each policy affects the market outcome
(the price buyers pay, the price sellers receive,
(the price buyers pay, the price sellers receive,
and eq’m quantity).
and eq’m quantity).
SUPPLY, DEMAND, AND GOVERNMENT POLICIES 3

EXAMPLE 1: The Market for Apartments

Rental P S
price of
apts
$800
Eq’m w/o
Eq’m w/o
price
price
controls
controls
D
Q
300
Quantity of
apartments

How Price Ceilings Affect Market Outcomes
A price ceiling P S
above the Price
eq’m price is $1000
ceiling
not binding –
has no effect $800
on the market
outcome.

D
Q
300



The eq’m price P S
($800) is above
the ceiling and
therefore illegal.
$800
The ceiling
is a binding Price
$500
constraint ceiling
on the price, shortage
D
causes a Q
250 400
shortage.



In the long run, P S
supply and
demand
are more $800
price-elastic.
Price
So, the $500
ceiling
shortage shortage
is larger. D
Q
150 450


Shortages and Rationing
 With a shortage, sellers must ration the goods
among buyers.
 Some rationing mechanisms: (1) Long lines
(2) Discrimination according to sellers’ biases
 These mechanisms are often unfair, and inefficient:
the goods do not necessarily go to the buyers who
value them most highly.
 In contrast, when prices are not controlled,
the rationing mechanism is efficient (the goods
go to the buyers that value them most highly)
and impersonal (and thus fair).

EXAMPLE 2: The Market for Unskilled Labor

Wage W S
paid to
unskilled
workers
$4

Eq’m w/o
Eq’m w/o
price
price
controls
controls
D
L
500
Quantity of
unskilled workers

How Price Floors Affect Market Outcomes
A price floor W S
below the
eq’m price is
not binding –
has no effect $4
on the market Price
outcome. $3
floor

D
L
500


How Price Floors Affect Market Outcomes
labor
The eq’m wage ($4) W surplus S
is below the floor Price
$5
and therefore floor
illegal.
$4
The floor
is a binding
constraint
on the wage,
D
causes a L
400 550
surplus (i.e.,
unemployment).


The Minimum Wage
Min wage laws unemp-
do not affect W loyment S
Min.
highly skilled $5
wage
workers.
They do affect $4
teen workers.
Studies:
A 10% increase
in the min wage D
L
raises teen 400 550
unemployment
by 1-3%.

ACTIVE LEARNING 1
Price controls The market for
P
140 hotel rooms
S
130
Determine
120
effects of:
110
A. $90 price 100
ceiling 90
B. $90 price 80 D
floor 70
60
C. $120 price
floor 50
40
0 Q
50 60 70 80 90 100 110 120 130
13

ACTIVE LEARNING 1
A. $90 price ceiling The market for
P
140 hotel rooms
The price S
130
falls to $90.
120
Buyers 110
demand 100
120 rooms, Price ceiling
90
sellers supply 80 D
90, leaving a shortage = 30
70
shortage. 60
50
40
0 Q
50 60 70 80 90 100 110 120 130
14

ACTIVE LEARNING 1
B. $90 price floor The market for
P
140 hotel rooms
Eq’m price is S
130
above the floor, 120
so floor is not
110
binding.
100
P = $100, 90
Price floor
Q = 100 rooms. 80 D
70
60
50
40
0 Q
50 60 70 80 90 100 110 120 130
15

ACTIVE LEARNING 1
C. $120 price floor The market for
P
140 hotel rooms
The price S
130 surplus = 60
rises to $120.
120
Buyers Price floor
110
demand 100
60 rooms, 90
sellers supply 80 D
120, causing a
70
surplus.
60
50
40
0 Q
50 60 70 80 90 100 110 120 130
16

Evaluating Price Controls
 Recall one of the Ten Principles from Chapter 1:
Markets are usually a good way
to organize economic activity.
 Prices are the signals that guide the allocation of
society’s resources. This allocation is altered
when policymakers restrict prices.
 Price controls often intended to help the poor,
but often hurt more than help.


Taxes
 The govt levies taxes on many goods & services
to raise revenue to pay for national defense,
public schools, etc.
 The govt can make buyers or sellers pay the tax.
 The tax can be a % of the good’s price,
or a specific amount for each unit sold.
 For simplicity, we analyze per-unit taxes only.


EXAMPLE 3: The Market for Pizza

Eq’m
Eq’m
P
w/o tax
w/o tax
S1

$10.00

D1

Q
500


A Tax on Buyers
The price tax on buyers
Hence, a buyersbuyers
Hence, a tax on pay Effects of a $1.50 per
is nowthe D curve down
shifts $1.50 higher than
shifts the D curve down unit tax on buyers
thethe amount ofP. tax. P
by market price the
by the amount of the tax.
P would have to fall S1
by $1.50 to make
buyers willing $10.00
Tax
to buy same Q
as before. $8.50
E.g., if P falls D1
from $10.00 to $8.50, D2
buyers still willing to Q
500
purchase 500 pizzas.


A Tax on Buyers
New eq’m: Effects of a $1.50 per
unit tax on buyers
Q = 450 P
Sellers S1
receive PB = $11.00
Tax
PS = $9.50 $10.00
PS = $9.50
Buyers pay
PB = $11.00
D1
Difference
D2
between them Q
= $1.50 = tax 450 500


The Incidence of a Tax:
how the burden of a tax is shared among
market participants
P
In our
S1
example, PB = $11.00
Tax
buyers pay $10.00
$1.00 more, PS = $9.50
sellers get
$0.50 less. D1
D2
Q
450 500


A Tax on Sellers
The tax effectively raises Effects of a $1.50 per
unit tax on sellers
sellers’ costs by
P S2
$1.50 per pizza. $11.50
Tax S1
Sellers will supply
500 pizzas
$10.00
only if
P rises to $11.50,
to compensate for
D1
this cost increase.

Hence, a tax on sellers shifts the
Hence, a tax on sellers shifts the Q
S curve up by the amount of the tax. 500
S curve up by the amount of the tax.


A Tax on Sellers
New eq’m: Effects of a $1.50 per
unit tax on sellers
Q = 450 P S2
Buyers pay S1
PB = $11.00 PB = $11.00
Tax
$10.00
Sellers
PS = $9.50
receive
PS = $9.50
D1
Difference
between them Q
= $1.50 = tax 450 500


The Outcome Is the Same in Both Cases!
The effects on P and Q, and the tax incidence are the
same whether the tax is imposed on buyers or sellers!

What matters P
is this: S1
PB = $11.00
Tax
A tax drives $10.00
a wedge PS = $9.50
between the
price buyers D1
pay and the
price sellers
Q
receive. 450 500


ACTIVE LEARNING 2
Effects of a tax The market for
P
140 hotel rooms
Suppose govt S
130
imposes a tax
120
on buyers of
110
$30 per room.
100
Find new 90
Q, PB, PS, 80 D
and incidence 70
of tax. 60
50
40
0 Q
50 60 70 80 90 100 110 120 130

ACTIVE LEARNING 2
Answers The market for
P
140 hotel rooms
S
130
Q = 80
120
PB = $110 PB = 110
100
PS = $80 Tax
90
PS = 80 D
Incidence 70
buyers: $10 60
sellers: $20 50
40
0 Q
50 60 70 80 90 100 110 120 130

Elasticity and Tax Incidence
CASE 1: Supply is more elastic than demand

P It’s easier
It’s easier
for sellers
for sellers
PB S than buyers
than buyers
Buyers’ share
of tax burden
to leave the
to leave the
Tax market.
market.
Price if no tax So buyers
So buyers
Sellers’ share PS bear most of
bear most of
of tax burden the burden
the burden
D of the tax.
of the tax.
Q


Elasticity and Tax Incidence
CASE 2: Demand is more elastic than supply

P It’s easier
It’s easier
S for buyers
for buyers
Buyers’ share than sellers
than sellers
of tax burden PB to leave the
to leave the
market.
market.
Price if no tax
Tax Sellers bear
Sellers bear
Sellers’ share most of the
most of the
of tax burden PS burden of
burden of
D the tax.
the tax.
Q


CASE STUDY: Who Pays the Luxury Tax?
 1990: Congress adopted a luxury tax on yachts,
private airplanes, furs, expensive cars, etc.
 Goal of the tax: raise revenue from those
who could most easily afford to pay –
wealthy consumers.
 But who really pays this tax?


CASE STUDY: Who Pays the Luxury Tax?

The market for yachts Demand is
Demand is
price-elastic.
price-elastic.
P
S
In the short run,
In the short run,
Buyers’ share
of tax burden PB supply is inelastic.
supply is inelastic.

Tax Hence,
Hence,
companies
companies
Sellers’ share
that build
that build
of tax burden PS
D yachts pay
yachts pay
most of
most of
Q the tax.
the tax.


CONCLUSION: Government Policies and
the Allocation of Resources
 Each of the policies in this chapter affects the
allocation of society’s resources.
 Example 1: A tax on pizza reduces eq’m Q.
With less production of pizza, resources
(workers, ovens, cheese) will become available
to other industries.
 Example 2: A binding minimum wage causes
a surplus of workers, a waste of resources.
 So, it’s important for policymakers to apply such
policies very carefully.

CHAPTER SUMMARY

 A price ceiling is a legal maximum on the price of a
good. An example is rent control. If the price
ceiling is below the eq’m price, it is binding and
causes a shortage.
 A price floor is a legal minimum on the price of a
good. An example is the minimum wage. If the
price floor is above the eq’m price, it is binding
and causes a surplus. The labor surplus caused
by the minimum wage is unemployment.
33

CHAPTER SUMMARY

 A tax on a good places a wedge between the price
buyers pay and the price sellers receive, and
causes the eq’m quantity to fall, whether the tax is
imposed on buyers or sellers.
 The incidence of a tax is the division of the burden
of the tax between buyers and sellers, and does
not depend on whether the tax is imposed on
buyers or sellers.
 The incidence of the tax depends on the price
elasticities of supply and demand.
34

Chapter06

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