Mankiw6e chap12

12
C H A P T E
R

The Open Economy Revisited:

the Mundell-Fleming Model
and the Exchange-Rate
MACROECONOMICS SIXTH EDITION
Regime
N. GREGORY MANKIW
PowerPoint® Slides by Ron Cronovich
© 2008 Worth Publishers, all rights reserved

In this chapter, you will learn…

 the Mundell-Fleming model
(IS-LM for the small open economy)
 causes and effects of interest rate differentials
 arguments for fixed vs. floating exchange rates
 how to derive the aggregate demand curve for a
small open economy

CHAPTER 12 The Open Economy Revisited slide 2

The Mundell-Fleming model

 Key assumption:
Small open economy with perfect capital mobility.
r = r*
 Goods market equilibrium – the IS* curve:
Y = C ( Y − T ) + I ( r * ) + G + NX ( e )

where
e = nominal exchange rate
= foreign currency per unit domestic currency


The IS* curve: Goods market eq’m
Y = C ( Y − T ) + I ( r * ) + G + NX ( e )

The IS* curve is drawn e
for a given value of r*.
Intuition for the slope:
↓ e ⇒ ↑ NX ⇒ ↑ Y

IS*
Y


The LM* curve: Money market eq’m
M P = L ( r * ,Y )
The LM* curve
e LM*
 is drawn for a given
value of r*.
 is vertical because:
given r*, there is
only one value of Y
that equates money
demand with supply, Y
regardless of e.

Equilibrium in the Mundell-Fleming
model
Y = C ( Y − T ) + I ( r * ) + G + NX ( e )
M P = L ( r * ,Y )
e LM*

equilibrium
exchange
rate

IS*
equilibrium Y
level of
income

Floating & fixed exchange rates

 In a system of floating exchange rates,
e is allowed to fluctuate in response to changing
economic conditions.
 In contrast, under fixed exchange rates,
the central bank trades domestic for foreign
currency at a predetermined price.
 Next, policy analysis –
 first, in a floating exchange rate system
 then, in a fixed exchange rate system

Fiscal policy under floating
exchange rates
Y = C ( Y − T ) + I ( r * ) + G + NX ( e )
M P = L ( r * ,Y )
e LM 1*
At any given value of e, e2

a fiscal expansion e1
increases Y,
I S 2*
shifting IS* to the right.
Results:
I S 1*
∆e > 0, ∆Y = 0 Y
Y1


Lessons about fiscal policy

 In a small open economy with perfect capital
mobility, fiscal policy cannot affect real GDP.
 “Crowding out”
 closed economy:
Fiscal policy crowds out investment by causing
the interest rate to rise.
 small open economy:
Fiscal policy crowds out net exports by causing
the exchange rate to appreciate.

Monetary policy under floating
exchange rates
Y = C ( Y − T ) + I ( r * ) + G + NX ( e )
M P = L ( r * ,Y )
e LM 1* LM 2*
An increase in M
shifts LM* right
because Y must rise
e1
to restore eq’m in
the money market. e2
Results: I S 1*
Y
∆e < 0, ∆Y > 0 Y1 Y2


Lessons about monetary policy
 Monetary policy affects output by affecting
the components of aggregate demand:
closed economy: ↑M ⇒ ↓r ⇒ ↑I ⇒ ↑Y
small open economy: ↑M ⇒ ↓e ⇒ ↑NX ⇒ ↑Y

 Expansionary mon. policy does not raise world
agg. demand, it merely shifts demand from
foreign to domestic products.
So, the increases in domestic income and
employment are at the expense of losses abroad.


Trade policy under floating
exchange rates
Y = C ( Y − T ) + I ( r * ) + G + NX ( e )
M P = L ( r * ,Y )
e LM 1*
At any given value of e,
a tariff or quota reduces e2
imports, increases NX,
e1
and shifts IS* to the right.
I S 2*
Results:
I S 1*
∆e > 0, ∆Y = 0 Y
Y1


Lessons about trade policy

 Import restrictions cannot reduce a trade deficit.
 Even though NX is unchanged, there is less
trade:
 the trade restriction reduces imports.
 the exchange rate appreciation reduces
exports.
 Less trade means fewer “gains from trade.”


Lessons about trade policy, cont.

 Import restrictions on specific products save jobs
in the domestic industries that produce those
products, but destroy jobs in export-producing
sectors.
 Hence, import restrictions fail to increase total
employment.
 Also, import restrictions create “sectoral shifts,”
which cause frictional unemployment.


Fixed exchange rates
 Under fixed exchange rates, the central bank
stands ready to buy or sell the domestic currency
for foreign currency at a predetermined rate.
 In the Mundell-Fleming model, the central bank
shifts the LM* curve as required to keep e at its
preannounced rate.
 This system fixes the nominal exchange rate.
In the long run, when prices are flexible,
the real exchange rate can move even if the
nominal rate is fixed.

Fiscal policy under fixed exchange
rates

Under floating rates,
a fiscalpolicy is ineffective
fiscal expansion
fiscal policy is ineffective e LM 1* LM 2*
would raise e.output.
at changing output.
at changing
To keepfixed rates,
e from rising,
Under fixed rates,
Under
the central bank very
must
fiscal policy is very
fiscal policy is
sell domesticchanging e1
effective at currency,
effective at changing
which increases M
output. I S 2*
output.
and shifts LM* right. I S 1*
Results: Y
Y1 Y2
∆e = 0, ∆Y > 0

Monetary policy under fixed
exchange rates
An increase in Mrates,
Under floating would
shift LM* right andis
monetary policy is
monetary policy reduce e.
e LM 1* LM 2*
very effective at
very effective at
To prevent the fall in e,
the central output.
changing bank must
changing output.
buy domestic rates,
Under fixed currency,
Under fixed rates,
which reduces M and
monetary policy cannot
monetary policy cannot e1
shifts LM* to affect output.
be used back left.
be used to affect output.
Results: I S 1*
Y
∆e = 0, ∆Y = 0 Y1


Trade policy under fixed exchange
rates
A restriction on imports
import restrictions
import restrictions
puts upward pressure on e.
do not affect Y or NX.
do not affect Y or NX. e LM 1* LM 2*
To keep e from rising,
Under fixed rates,
Under fixed rates,
the central bank must
import restrictions
import restrictions
sell domestic currency,
increase Y andMNX.
increase Y and NX.
which increases e1
But, theseLM* right.
But, shifts gains come
and these gains come
at the expense of other I S 2*
at the expense of other
countries: the policy
Results:
countries: the policy I S 1*
merely shifts demand from Y
merely shifts demand from
∆e = 0, ∆Y > 0 Y1 Y2
foreign to domestic goods.
foreign to domestic goods.

Summary of policy effects in the
Mundell-Fleming model

type of exchange rate regime:

floating fixed
impact on:

Policy Y e NX Y e NX

fiscal expansion 0 ↑ ↓ ↑ 0 0

mon. expansion ↑ ↓ ↑ 0 0 0

import restriction 0 ↑ 0 ↑ 0 ↑


Interest-rate differentials

Two reasons why r may differ from r*
 country risk: The risk that the country’s borrowers
will default on their loan repayments because of
political or economic turmoil.
Lenders require a higher interest rate to
compensate them for this risk.
 expected exchange rate changes: If a country’s
exchange rate is expected to fall, then its borrowers
must pay a higher interest rate to compensate
lenders for the expected currency depreciation.


Differentials in the M-F model
r = r * +θ
where θ (Greek letter “theta”) is a risk premium,
assumed exogenous.
Substitute the expression for r into the
IS* and LM* equations:
Y = C ( Y − T ) + I ( r * + θ ) + G + NX ( e )

M P = L ( r * + θ ,Y )


The effects of an increase in θ

IS* shifts left, because
↑θ ⇒ ↑r ⇒ ↓I e LM 1* LM 2*
LM* shifts right, because
e1
↑θ ⇒ ↑r ⇒ ↓(M/P)d,
so Y must rise to restore
money market eq’m. e2 I S 1*
Results: I S 2*
∆e < 0, ∆Y > 0 Y
Y1 Y2


The effects of an increase in θ

 The fall in e is intuitive:
An increase in country risk or an expected
depreciation makes holding the country’s currency
less attractive.
Note: an expected depreciation is a
self-fulfilling prophecy.
 The increase in Y occurs because
the boost in NX (from the depreciation)
is greater than the fall in I (from the rise in r ).


Why income might not rise

 The central bank may try to prevent the
depreciation by reducing the money supply.
 The depreciation might boost the price of
imports enough to increase the price level
(which would reduce the real money supply).
 Consumers might respond to the increased risk
by holding more money.
Each of the above would shift LM* leftward.


CASE STUDY:
The Mexican peso crisis
35
U.S. Cents per Mexican Peso

30

25

20

15

10
7/10/94 8/29/94 10/18/94 12/7/94 1/26/95 3/17/95 5/6/95


The Peso crisis didn’t just hurt
Mexico
 U.S. goods more expensive to Mexicans
 U.S. firms lost revenue
 Hundreds of bankruptcies along
U.S.-Mexican border
 Mexican assets worth less in dollars
 Reduced wealth of millions of U.S. citizens


Understanding the crisis
 In the early 1990s, Mexico was an attractive place
for foreign investment.
 During 1994, political developments caused an
increase in Mexico’s risk premium (θ ):
 peasant uprising in Chiapas
 assassination of leading presidential candidate
 Another factor:
The Federal Reserve raised U.S. interest rates
several times during 1994 to prevent U.S. inflation.
(∆r* > 0)

Understanding the crisis

 These events put downward pressure on the
peso.
 Mexico’s central bank had repeatedly promised
foreign investors that it would not allow the peso’s
value to fall,
so it bought pesos and sold dollars to
“prop up” the peso exchange rate.
 Doing this requires that Mexico’s central bank
have adequate reserves of dollars.
Did it?

Dollar reserves of Mexico’s central
bank

December 1993 ……………… $28 billion
December 1993 ……………… $28 billion
August 17, 1994 ……………… $17 billion
August 17, 1994 ……………… $17 billion
December 1, 1994 …………… $ 9 billion
December 1, 1994 …………… $ 9 billion
December 15, 1994 ………… $ 7 billion
December 15, 1994 ………… $ 7 billion

During 1994, Mexico’s central bank hid the
fact that its reserves were being depleted.


 the disaster 
 Dec. 20: Mexico devalues the peso by 13%
(fixes e at 25 cents instead of 29 cents)
 Investors are SHOCKED! – they had no idea
Mexico was running out of reserves.
 ↑ θ , investors dump their Mexican assets and
pull their capital out of Mexico.
 Dec. 22: central bank’s reserves nearly gone.
It abandons the fixed rate and lets e float.
 In a week, e falls another 30%.

The rescue package

 1995: U.S. & IMF set up $50b line of credit to
provide loan guarantees to Mexico’s govt.
 This helped restore confidence in Mexico,
reduced the risk premium.
 After a hard recession in 1995, Mexico began a
strong recovery from the crisis.


CASE STUDY:
The Southeast Asian crisis 1997-
98
 Problems in the banking system eroded
international confidence in SE Asian economies.
 Risk premiums and interest rates rose.
 Stock prices fell as foreign investors sold assets
and pulled their capital out.
 Falling stock prices reduced the value of collateral
used for bank loans, increasing default rates,
which exacerbated the crisis.
 Capital outflows depressed exchange rates.

Data on the SE Asian crisis
nominal GDP
exchange rate stock market
% change from % change from
% change
7/97 to 1/98 7/97 to 1/98
1997-98
Indonesia -59.4% -32.6% -16.2%
Japan -12.0% -18.2% -4.3%
Malaysia -36.4% -43.8% -6.8%
Singapore -15.6% -36.0% -0.1%
S. Korea -47.5% -21.9% -7.3%
Taiwan -14.6% -19.7% n.a.
Thailand -48.3% -25.6% -1.2%
U.S. n.a. 2.7% 2.3%

Floating vs. fixed exchange rates

Argument for floating rates:
 allows monetary policy to be used to pursue other
goals (stable growth, low inflation).

Arguments for fixed rates:
 avoids uncertainty and volatility, making
international transactions easier.
 disciplines monetary policy to prevent excessive
money growth & hyperinflation.


The Impossible Trinity

A nation cannot have free
capital flows, independent Free capital
monetary policy, and a flows
fixed exchange rate
simultaneously. Option 1 Option 2
(U.S.) (Hong Kong)
A nation must choose
one side of this
triangle and
Independent Fixed
give up the Option 3
monetary exchange
opposite policy
(China)
corner. rate

CASE STUDY:
The Chinese Currency
Controversy
 1995-2005: China fixed its exchange rate at 8.28
yuan per dollar, and restricted capital flows.
 Many observers believed that the yuan was
significantly undervalued, as China was
accumulating large dollar reserves.
 U.S. producers complained that China’s cheap
yuan gave Chinese producers an unfair advantage.
 President Bush asked China to let its currency float;
Others in the U.S. wanted tariffs on Chinese goods.

CASE STUDY:
The Chinese Currency
Controversy
 If China lets the yuan float, it may indeed
appreciate.
 However, if China also allows greater capital
mobility, then Chinese citizens may start moving
their savings abroad.
 Such capital outflows could cause the yuan to
depreciate rather than appreciate.


Mundell-Fleming and the AD curve

 So far in M-F model, P has been fixed.
 Next: to derive the AD curve, consider the impact of
a change in P in the M-F model.
 We now write the M-F equations as:
( IS* ) Y = C ( Y − T ) + I ( r * ) + G + NXε )
(

( LM* ) M P = L ( r * ,Y )
(Earlier in this chapter, P was fixed, so we
could write NX as a function of e instead of ε .)

Deriving the AD curve
ε LM*(P2 ) LM*(P1 )
Why AD curve has
ε2
negative slope:
ε1
↑P ⇒ ↓(M/P)
IS*
⇒ LM shifts left Y2 Y1 Y
P
⇒ ↑ε
P2
⇒ ↓NX P1
⇒ ↓Y AD
Y2 Y1 Y

From the short run to the long run
ε LM*(P1 ) LM*(P2 )
If Y1 < Y ,
then there is ε1
downward pressure ε2
on prices. IS*
Over time, P will Y1 Y Y
P LRAS
move down, causing
(M/P )↑ P1 SRAS1
ε↓ P2 SRAS2
NX ↑ AD
Y↑ Y1 Y Y

Large: Between small and
closed
 Many countries – including the U.S. – are neither
closed nor small open economies.
 A large open economy is between the polar
cases of closed & small open.
 Consider a monetary expansion:
 Like in a closed economy,
∆M > 0 ⇒ ↓r ⇒ ↑I (though not as much)
 Like in a small open economy,
∆M > 0 ⇒ ↓ε ⇒ ↑NX (though not as much)

Chapter Summary

1. Mundell-Fleming model
 the IS-LM model for a small open economy.
 takes P as given.
 can show how policies and shocks affect income
and the exchange rate.
2. Fiscal policy
 affects income under fixed exchange rates, but not
under floating exchange rates.


Chapter Summary

3. Monetary policy
 affects income under floating exchange rates.
 under fixed exchange rates, monetary policy is not
available to affect output.
4. Interest rate differentials
 exist if investors require a risk premium to hold a
country’s assets.
 An increase in this risk premium raises domestic
interest rates and causes the country’s exchange
rate to depreciate.


Chapter Summary

5. Fixed vs. floating exchange rates
 Under floating rates, monetary policy is available for
can purposes other than maintaining exchange rate
stability.
 Fixed exchange rates reduce some of the
uncertainty in international transactions.


Mankiw6e chap12

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