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When conducting monetary and fiscal policy, policymakers often look be-
yond their own country’s borders. Even if domestic prosperity is their sole ob-
jective, it is necessary for them to consider the rest of the world. The
international flow of goods and services and the international flow of capital
can affect an economy in profound ways. Policymakers ignore these effects at
their peril.
In this chapter we extend our analysis of aggregate demand to include inter-
national trade and finance. The model developed in this chapter, called the
Mundell–Fleming model, is an open-economy version of the IS–LM model.
Both models stress the interaction between the goods market and the money
market. Both models assume that the price level is fixed and then show what
causes short-run fluctuations in aggregate income (or, equivalently, shifts in the
aggregate demand curve).The key difference is that the IS–LM model assumes a
closed economy, whereas the Mundell–Fleming model assumes an open econ-
omy.The Mundell–Fleming model extends the short-run model of national in-
come from Chapters 10 and 11 by including the effects of international trade
and finance from Chapter 5.
The Mundell–Fleming model makes one important and extreme assump-
tion: it assumes that the economy being studied is a small open economy with
perfect capital mobility.That is, the economy can borrow or lend as much as it
wants in world financial markets and, as a result, the economy’s interest rate is
determined by the world interest rate. One virtue of this assumption is that it
simplifies the analysis: once the interest rate is determined, we can concentrate
our attention on the role of the exchange rate. In addition, for some
economies, such as Belgium or the Netherlands, the assumption of a small
open economy with perfect capital mobility is a good one.Yet this assump-
tion—and thus the Mundell–Fleming model—does not apply exactly to a
large open economy such as the United States. In the conclusion to this chap-
ter (and more fully in the appendix), we consider what happens in the more
complex case in which international capital mobility is less than perfect or a
nation is so large it can influence world financial markets.
One lesson from the Mundell–Fleming model is that the behavior of an econ-
omy depends on the exchange-rate system it has adopted.We begin by assuming
that the economy operates with a floating exchange rate.That is, we assume that
the central bank allows the exchange rate to adjust to changing economic condi-
tions.We then examine how the economy operates under a fixed exchange rate,
12
Aggregate Demand in the
Open Economy
CHAPTER TWELVE
312 |
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and we discuss whether a floating or fixed exchange rate is better.This question
has been important in recent years, as many nations around the world have de-
bated what exchange-rate system to adopt.
12-1 The Mundell–Fleming Model
In this section we build the Mundell–Fleming model, and in the following sec-
tions we use the model to examine the impact of various policies. As you will
see, the Mundell–Fleming model is built from components we have used in pre-
vious chapters. But these pieces are put together in a new way to address a new
set of questions.
1
The Key Assumption: Small Open Economy With
Perfect Capital Mobility
Let’s begin with the assumption of a small open economy with perfect capital
mobility. As we saw in Chapter 5, this assumption means that the interest rate in
this economy r is determined by the world interest rate r*. Mathematically, we
can write this assumption as
r = r*.
This world interest rate is assumed to be exogenously fixed because the economy is
sufficiently small relative to the world economy that it can borrow or lend as much
as it wants in world financial markets without affecting the world interest rate.
Although the idea of perfect capital mobility is expressed with a simple equa-
tion, it is important not to lose sight of the sophisticated process that this equa-
tion represents. Imagine that some event were to occur that would normally raise
the interest rate (such as a decline in domestic saving). In a small open economy,
the domestic interest rate might rise by a little bit for a short time, but as soon as
it did, foreigners would see the higher interest rate and start lending to this coun-
try (by, for instance, buying this country’s bonds).The capital inflow would drive
the domestic interest rate back toward r*. Similarly, if any event were ever to start
driving the domestic interest rate downward, capital would flow out of the
country to earn a higher return abroad, and this capital outflow would drive the
domestic interest rate back upward toward r*. Hence, the r = r* equation repre-
sents the assumption that the international flow of capital is rapid enough to
keep the domestic interest rate equal to the world interest rate.
CHAPTER 12 Aggregate Demand in the Open Economy | 313
1
The Mundell–Fleming model was developed in the early 1960s. Mundell’s contributions are col-
lected in Robert A. Mundell, International Economics (New York: Macmillan, 1968). For Fleming’s
contribution, see J. Marcus Fleming,“Domestic Financial Policies Under Fixed and Under Floating
Exchange Rates,’’ IMF Staff Papers 9 (November 1962): 369–379. In 1999, Robert Mundell was
awarded the Nobel Prize for his work in open-economy macroeconomics.
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The Goods Market and the IS* Curve
The Mundell–Fleming model describes the market for goods and services much
as the IS–LM model does, but it adds a new term for net exports. In particular,
the goods market is represented with the following equation:
Y = C(Y ? T ) + I(r*) + G + NX(e).
This equation states that aggregate income Y is the sum of consumption C,in-
vestment I, government purchases G, and net exports NX. Consumption de-
pends positively on disposable income Y ? T. Investment depends negatively on
the interest rate, which equals the world interest rate r*. Net exports depend
negatively on the exchange rate e.As before, we define the exchange rate e as the
amount of foreign currency per unit of domestic currency—for example, e
might be 100 yen per dollar.
You may recall that in Chapter 5 we related net exports to the real exchange
rate (the relative price of goods at home and abroad) rather than the nominal ex-
change rate (the relative price of domestic and foreign currencies). If e is the
nominal exchange rate, then the real exchange rate
e
equals eP/P*, where P is
the domestic price level and P* is the foreign price level.The Mundell–Fleming
model, however, assumes that the price levels at home and abroad are fixed, so
the real exchange rate is proportional to the nominal exchange rate. That is,
when the nominal exchange rate appreciates (say, from 100 to 120 yen per dol-
lar), foreign goods become cheaper compared to domestic goods, and this causes
exports to fall and imports to rise.
We can illustrate this equation for goods market equilibrium on a graph in
which income is on the horizontal axis and the exchange rate is on the vertical
axis.This curve is shown in panel (c) of Figure 12-1 and is called the IS* curve.
The new label reminds us that the curve is drawn holding the interest rate con-
stant at the world interest rate r*.
The IS* curve slopes downward because a higher exchange rate reduces net
exports, which in turn lowers aggregate income. To show how this works, the
other panels of Figure 12-1 combine the net-exports schedule and the Keynes-
ian cross to derive the IS* curve. In panel (a), an increase in the exchange rate
from e
1
to e
2
lowers net exports from NX(e
1
) to NX(e
2
). In panel (b), the reduc-
tion in net exports shifts the planned-expenditure schedule downward and thus
lowers income from Y
1
to Y
2
.The IS* curves summarizes this relationship be-
tween the exchange rate e and income Y.
The Money Market and the LM* Curve
The Mundell–Fleming model represents the money market with an equation
that should be familiar from the IS–LM model, with the additional assumption
that the domestic interest rate equals the world interest rate:
M/P = L(r*, Y ).
314 | PART IV Business Cycle Theory: The Economy in the Short Run
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This equation states that the supply of real money balances, M/P, equals the
demand, L(r, Y ).The demand for real balances depends negatively on the in-
terest rate, which is now set equal to the world interest rate r*, and positively
on income Y. The money supply M is an exogenous variable controlled by
the central bank, and because the Mundell–Fleming model is designed to an-
alyze short-run fluctuations, the price level P is also assumed to be exoge-
nously fixed.
We can represent this equation graphically with a vertical LM* curve, as in
panel (b) of Figure 12-2.The LM* curve is vertical because the exchange rate
does not enter into the LM* equation. Given the world interest rate, the LM*
equation determines aggregate income, regardless of the exchange rate. Figure
12-2 shows how the LM* curve arises from the world interest rate and the LM
curve, which relates the interest rate and income.
CHAPTER 12 Aggregate Demand in the Open Economy | 315
figure 12-1
Expenditure, E
Exchange
rate, e
Exchange rate, e
Income,
output, Y
Income,
output, Y
Net
exports,
NX
Y
1
Y
2
IS*
NX(e
1
)NX(e
2
)
H9004NX
H9004NX
e
1
e
2
Actual
expenditure
Planned
expenditure
45°
Y
1
Y
2
e
1
e
2
(a) The Net-Exports Schedule
(b) The Keynesian Cross
(c) The IS* Curve
2. . . . lowers
net exports, . . .
3. . . . which
shifts planned
expenditure
downward . . .
5. The IS* curve
summarizes these
changes in the goods
market equilibrium.
1. An
increase in
the exchange
rate . ..
4. . . . and
lowers
income.
The IS* Curve The IS* curve is
derived from the net-exports
schedule and the Keynesian cross.
Panel (a) shows the net-exports
schedule: an increase in the
exchange rate from e
1
to e
2
lowers
net exports from NX(e
1
) to NX(e
2
).
Panel (b) shows the Keynesian
cross: a decrease in net exports from
NX(e
1
) to NX(e
2
) shifts the planned-
expenditure schedule downward
and reduces income from Y
1
to Y
2
.
Panel (c) shows the IS* curve
summarizing this relationship
between the exchange rate and
income: the higher the exchange
rate, the lower the level of income.
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Putting the Pieces Together
According to the Mundell–Fleming model, a small open economy with perfect
capital mobility can be described by two equations:
Y = C(Y ? T ) + I(r*) + G + NX(e) IS*,
M/P = L(r*, Y ) LM*.
The first equation describes equilibrium in the goods market, and the second
equation describes equilibrium in the money market. The exogenous variables
are fiscal policy G and T, monetary policy M, the price level P, and the world in-
terest rate r*.The endogenous variables are income Y and the exchange rate e.
Figure 12-3 illustrates these two relationships.The equilibrium for the econ-
omy is found where the IS* curve and the LM* curve intersect.This intersection
316 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-2
Interest rate, r
Exchange rate, e
Income, output, Y
Income, output, Y
1. The money
market
equilibrium
condition . . .
2. . . . and
the world
interest rate . . .
3. . . . determine
the level of
income.
(a) The LM Curve
(b) The LM* Curve
LM
r H11005 r*
LM*
The LM* Curve Panel (a) shows the standard LM
curve [which graphs the equation M/P = L(r, Y)]
together with a horizontal line representing the
world interest rate r*. The intersection of these
two curves determines the level of income,
regardless of the exchange rate. Therefore, as
panel (b) shows, the LM* curve is vertical.
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shows the exchange rate and the level of income at which both the goods market
and the money market are in equilibrium. With this diagram, we can use the
Mundell–Fleming model to show how aggregate income Y and the exchange
rate e respond to changes in policy.
12-2 The Small Open Economy Under Floating
Exchange Rates
Before analyzing the impact of policies in an open economy, we must specify the
international monetary system in which the country has chosen to operate.We
start with the system relevant for most major economies today: floating ex-
change rates. Under floating exchange rates, the exchange rate is allowed to
fluctuate in response to changing economic conditions.
Fiscal Policy
Suppose that the government stimulates domestic spending by increasing govern-
ment purchases or by cutting taxes. Because such expansionary fiscal policy in-
creases planned expenditure, it shifts the IS* curve to the right, as in Figure 12-4.
As a result, the exchange rate appreciates, whereas the level of income remains
the same.
Notice that fiscal policy has very different effects in a small open economy
than it does in a closed economy. In the closed-economy IS–LM model, a
fiscal expansion raises income, whereas in a small open economy with a floating
exchange rate, a fiscal expansion leaves income at the same level. Why the
CHAPTER 12 Aggregate Demand in the Open Economy | 317
figure 12-3
Exchange rate, e
Income, output, Y
Equilibrium
exchange rate
Equilibrium
income
LM*
IS*
The Mundell–Fleming Model
This graph of the Mundell–
Fleming model plots the
goods market equilibrium
condition IS* and the money
market equilibrium condition
LM*. Both curves are drawn
holding the interest rate
constant at the world interest
rate. The intersection of these
two curves shows the level of
income and the exchange rate
that satisfy equilibrium both in
the goods market and in the
money market.
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difference? When income rises in a closed economy, the interest rate rises,
because higher income increases the demand for money.That is not possible in a
small open economy: as soon as the interest rate tries to rise above the world
interest rate r*, capital flows in from abroad.This capital inflow increases the de-
mand for the domestic currency in the market for foreign-currency exchange
and, thus, bids up the value of the domestic currency.The appreciation of the ex-
change rate makes domestic goods expensive relative to foreign goods, and this
reduces net exports.The fall in net exports offsets the effects of the expansionary
fiscal policy on income.
Why is the fall in net exports so great that it renders fiscal policy powerless to
influence income? To answer this question, consider the equation that describes
the money market:
M/P = L(r, Y ).
In both closed and open economies, the quantity of real money balances sup-
plied M/P is fixed, and the quantity demanded (determined by r and Y ) must
equal this fixed supply. In a closed economy, a fiscal expansion causes the
equilibrium interest rate to rise.This increase in the interest rate (which re-
duces the quantity of money demanded) allows equilibrium income to rise
(which increases the quantity of money demanded). By contrast, in a small
open economy, r is fixed at r*, so there is only one level of income that
can satisfy this equation, and this level of income does not change when fiscal
policy changes.Thus, when the government increases spending or cuts taxes,
the appreciation of the exchange rate and the fall in net exports must be
large enough to offset fully the normal expansionary effect of the policy on
income.
318 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-4
Exchange rate, e
Income, output, Y
Equilibrium
exchange rate
LM*
IS*
2
IS*
1
2. . . . which
raises the
exchange
rate . . .
3. . . . and
leaves income
unchanged.
1. Expansionary fiscal
policy shifts the IS*
curve to the right, ...
A Fiscal Expansion Under
Floating Exchange Rates An
increase in government
purchases or a decrease in taxes
shifts the IS* curve to the right.
This raises the exchange rate but
has no effect on income.
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Monetary Policy
Suppose now that the central bank increases the money supply. Because the price
level is assumed to be fixed, the increase in the money supply means an increase
in real balances.The increase in real balances shifts the LM* curve to the right, as
in Figure 12-5. Hence, an increase in the money supply raises income and lowers
the exchange rate.
CHAPTER 12 Aggregate Demand in the Open Economy | 319
figure 12-5
Exchange rate, e
Income, output, Y
2. . . . which
lowers the
exchange
rate . . .
3. . . . and
raises income.
1. A monetary expan-
sion shifts the LM*
curve to the right, ...
LM*
1
IS*
LM*
2
A Monetary Expansion Under
Floating Exchange Rates An
increase in the money supply
shifts the LM* curve to the
right, lowering the exchange
rate and raising income.
Although monetary policy influences income in an open economy, as it does
in a closed economy, the monetary transmission mechanism is different. Recall
that in a closed economy an increase in the money supply increases spending be-
cause it lowers the interest rate and stimulates investment. In a small open econ-
omy, the interest rate is fixed by the world interest rate.As soon as an increase in
the money supply puts downward pressure on the domestic interest rate, capital
flows out of the economy as investors seek a higher return elsewhere.This capital
outflow prevents the domestic interest rate from falling. In addition, because the
capital outflow increases the supply of the domestic currency in the market for
foreign-currency exchange, the exchange rate depreciates. The fall in the ex-
change rate makes domestic goods inexpensive relative to foreign goods and,
thereby, stimulates net exports. Hence, in a small open economy, monetary policy
influences income by altering the exchange rate rather than the interest rate.
Trade Policy
Suppose that the government reduces the demand for imported goods by impos-
ing an import quota or a tariff.What happens to aggregate income and the ex-
change rate?
Because net exports equal exports minus imports, a reduction in imports
means an increase in net exports.That is, the net-exports schedule shifts to the
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right, as in Figure 12-6. This shift in the net-exports schedule increases
planned expenditure and thus moves the IS* curve to the right. Because the
LM* curve is vertical, the trade restriction raises the exchange rate but does
not affect income.
Often a stated goal of policies to restrict trade is to alter the trade balance NX.
Yet, as we first saw in Chapter 5, such policies do not necessarily have that effect.
The same conclusion holds in the Mundell–Fleming model under floating ex-
change rates. Recall that
NX(e) = Y ? C(Y ? T ) ? I(r*) ? G.
320 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-6
Exchange rate, e
Exchange rate, e
Net exports, NX
Income, output, Y
NX
2
NX
1
IS*
2
LM*
IS*
1
3. . . . increasing
the exchange
rate . . .
4. . . . and
leaving income
the same.
(a) The Shift in the Net-Exports Schedule
1. A trade restriction
shifts the NX curve
outward, ...
(b) The Change in the Economy
,
s Equilibrium
2. . . . which shifts the
IS* curve outward, ...
A Trade Restriction Under
Floating Exchange Rates A
tariff or an import quota
shifts the net-exports
schedule in panel (a) to the
right. As a result, the IS*
curve in panel (b) shifts to
the right, raising the exchange
rate and leaving income
unchanged.
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Because a trade restriction does not affect income, consumption, investment, or
government purchases, it does not affect the trade balance.Although the shift in
the net-exports schedule tends to raise NX, the increase in the exchange rate re-
duces NX by the same amount.
12-3 The Small Open Economy Under Fixed
Exchange Rates
We now turn to the second type of exchange-rate system: fixed exchange
rates. In the 1950s and 1960s, most of the world’s major economies, including
the United States, operated within the Bretton Woods system—an international
monetary system under which most governments agreed to fix exchange rates.
The world abandoned this system in the early 1970s, and exchange rates were al-
lowed to float. Some European countries later reinstated a system of fixed ex-
change rates among themselves, and some economists have advocated a return to
a worldwide system of fixed exchange rates. In this section we discuss how such
a system works, and we examine the impact of economic policies on an econ-
omy with a fixed exchange rate.
How a Fixed-Exchange-Rate System Works
Under a system of fixed exchange rates, a central bank stands ready to buy or sell
the domestic currency for foreign currencies at a predetermined price. For ex-
ample, suppose that the Fed announced that it was going to fix the exchange rate
at 100 yen per dollar. It would then stand ready to give $1 in exchange for 100
yen or to give 100 yen in exchange for $1. To carry out this policy, the Fed
would need a reserve of dollars (which it can print) and a reserve of yen (which
it must have purchased previously).
A fixed exchange rate dedicates a country’s monetary policy to the single
goal of keeping the exchange rate at the announced level. In other words, the
essence of a fixed-exchange-rate system is the commitment of the central
bank to allow the money supply to adjust to whatever level will ensure that
the equilibrium exchange rate equals the announced exchange rate. More-
over, as long as the central bank stands ready to buy or sell foreign currency at
the fixed exchange rate, the money supply adjusts automatically to the neces-
sary level.
To see how fixing the exchange rate determines the money supply, consider
the following example. Suppose that the Fed announces that it will fix the ex-
change rate at 100 yen per dollar, but, in the current equilibrium with the cur-
rent money supply, the exchange rate is 150 yen per dollar. This situation is
illustrated in panel (a) of Figure 12-7. Notice that there is a profit opportunity: an
arbitrageur could buy 300 yen in the marketplace for $2, and then sell the yen to
the Fed for $3, making a $1 profit.When the Fed buys these yen from the arbi-
trageur, the dollars it pays for them automatically increase the money supply. The
CHAPTER 12 Aggregate Demand in the Open Economy | 321
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rise in the money supply shifts the LM* curve to the right, lowering the equilib-
rium exchange rate. In this way, the money supply continues to rise until the
equilibrium exchange rate falls to the announced level.
Conversely, suppose that when the Fed announces that it will fix the ex-
change rate at 100 yen per dollar, the equilibrium is 50 yen per dollar. Panel (b)
of Figure 12-7 shows this situation. In this case, an arbitrageur could make a
profit by buying 100 yen from the Fed for $1 and then selling the yen in the
marketplace for $2.When the Fed sells these yen, the $1 it receives automati-
cally reduces the money supply.The fall in the money supply shifts the LM*
curve to the left, raising the equilibrium exchange rate. The money supply
continues to fall until the equilibrium exchange rate rises to the announced
level.
It is important to understand that this exchange-rate system fixes the nominal
exchange rate.Whether it also fixes the real exchange rate depends on the time
horizon under consideration. If prices are flexible, as they are in the long run, then
the real exchange rate can change even while the nominal exchange rate is fixed.
Therefore, in the long run described in Chapter 5, a policy to fix the nominal
exchange rate would not influence any real variable, including the real exchange
rate.A fixed nominal exchange rate would influence only the money supply and
the price level.Yet in the short run described by the Mundell–Fleming model,
prices are fixed, so a fixed nominal exchange rate implies a fixed real exchange
rate as well.
322 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-7
Exchange rate, e Exchange rate, e
Income, output, YIncome, output, Y
Equilibrium
exchange
rate
Fixed exchange
rate
Fixed
exchange
rate
Equilibrium
exchange
rate
(a) The Equilibrium Exchange Rate Is Greater
Than the Fixed Exchange Rate
LM*
1
LM*
2
LM*
1
LM*
2
IS*
(b) The Equilibrium Exchange Rate Is Less
Than the Fixed Exchange Rate
IS*
How a Fixed Exchange Rate Governs the Money Supply In panel (a), the equilibrium
exchange rate initially exceeds the fixed level. Arbitrageurs will buy foreign currency in
foreign-exchange markets and sell it to the Fed for a profit. This process automatically
increases the money supply, shifting the LM* curve to the right and lowering the
exchange rate. In panel (b), the equilibrium exchange rate is initially below the fixed
level. Arbitrageurs will buy dollars in foreign-exchange markets and use them to buy
foreign currency from the Fed. This process automatically reduces the money supply,
shifting the LM* curve to the left and raising the exchange rate.
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Fiscal Policy
Let’s now examine how economic policies affect a small open economy with a
fixed exchange rate. Suppose that the government stimulates domestic spending
by increasing government purchases or by cutting taxes.This policy shifts the IS*
curve to the right, as in Figure 12-8, putting upward pressure on the exchange
rate. But because the central bank stands ready to trade foreign and domestic cur-
rency at the fixed exchange rate, arbitrageurs quickly respond to the rising ex-
change rate by selling foreign currency to the central bank, leading to an
automatic monetary expansion. The rise in the money supply shifts the LM*
curve to the right.Thus, under a fixed exchange rate, a fiscal expansion raises ag-
gregate income.
CHAPTER 12 Aggregate Demand in the Open Economy | 323
CASE STUDY
The International Gold Standard
During the late nineteenth and early twentieth centuries, most of the world’s
major economies operated under a gold standard. Each country maintained a re-
serve of gold and agreed to exchange one unit of its currency for a specified
amount of gold.Through the gold standard, the world’s economies maintained a
system of fixed exchange rates.
To see how an international gold standard fixes exchange rates, suppose that
the U.S.Treasury stands ready to buy or sell 1 ounce of gold for $100, and the
Bank of England stands ready to buy or sell 1 ounce of gold for 100 pounds.To-
gether, these policies fix the rate of exchange between dollars and pounds: $1
must trade for 1 pound. Otherwise, the law of one price would be violated, and
it would be profitable to buy gold in one country and sell it in the other.
For example, suppose that the exchange rate were 2 pounds per dollar. In
this case, an arbitrageur could buy 200 pounds for $100, use the pounds to buy
2 ounces of gold from the Bank of England, bring the gold to the United
States, and sell it to the Treasury for $200—making a $100 profit. Moreover, by
bringing the gold to the United States from England, the arbitrageur would in-
crease the money supply in the United States and decrease the money supply
in England.
Thus, during the era of the gold standard, the international transport of
gold by arbitrageurs was an automatic mechanism adjusting the money supply
and stabilizing exchange rates. This system did not completely fix exchange
rates, because shipping gold across the Atlantic was costly.Yet the international
gold standard did keep the exchange rate within a range dictated by trans-
portation costs. It thereby prevented large and persistent movements in ex-
change rates.
2
2
For more on how the gold standard worked, see the essays in Barry Eichengreen, ed., The Gold
Standard in Theory and History (New York: Methuen, 1985).
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324 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-8
2. . . . a fiscal
expansion shifts
the IS* curve
to the right, ...
Exchange rate, e
Income, output, Y
LM*
1
LM*
2
IS*
1
Y
1
Y
2
IS*
2
1. With a fixed
exchange
rate . . .
4. . . . and
raises income.
3. . . . which
induces a shift
in the LM*
curve . . .
A Fiscal Expansion Under
Fixed Exchange Rates A
fiscal expansion shifts the IS*
curve to the right. To
maintain the fixed exchange
rate, the Fed must increase
the money supply, thereby
shifting the LM* curve to the
right. Hence, in contrast to
the case of floating exchange
rates, under fixed exchange
rates a fiscal expansion raises
income.
figure 12-9
Exchange rate, e
Income, output, Y
Fixed
exchange
rate
LM*
IS*
A Monetary Expansion Under
Fixed Exchange Rates If the Fed
tries to increase the money
supply—for example, by buying
bonds from the public—it will
put downward pressure on the
exchange rate. To maintain the
fixed exchange rate, the money
supply and the LM* curve must
return to their initial positions.
Hence, under fixed exchange
rates, normal monetary policy is
ineffectual.
Monetary Policy
Imagine that a central bank operating with a fixed exchange rate were to try to
increase the money supply—for example, by buying bonds from the public.What
would happen? The initial impact of this policy is to shift the LM* curve to the
right, lowering the exchange rate, as in Figure 12-9. But, because the central
bank is committed to trading foreign and domestic currency at a fixed exchange
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rate, arbitrageurs quickly respond to the falling exchange rate by selling the do-
mestic currency to the central bank, causing the money supply and the LM*
curve to return to their initial positions. Hence, monetary policy as usually con-
ducted is ineffectual under a fixed exchange rate. By agreeing to fix the exchange
rate, the central bank gives up its control over the money supply.
A country with a fixed exchange rate can, however, conduct a type of mone-
tary policy: it can decide to change the level at which the exchange rate is fixed.
A reduction in the value of the currency is called a devaluation, and an increase
in its value is called a revaluation. In the Mundell–Fleming model, a devalua-
tion shifts the LM* curve to the right; it acts like an increase in the money sup-
ply under a floating exchange rate. A devaluation thus expands net exports and
raises aggregate income. Conversely, a revaluation shifts the LM* curve to the
left, reduces net exports, and lowers aggregate income.
CHAPTER 12 Aggregate Demand in the Open Economy | 325
CASE STUDY
Devaluation and the Recovery From the Great Depression
The Great Depression of the 1930s was a global problem.Although events in the
United States may have precipitated the downturn, all of the world’s major
economies experienced huge declines in production and employment.Yet not all
governments responded to this calamity in the same way.
One key difference among governments was how committed they were to
the fixed exchange rate set by the international gold standard. Some countries,
such as France, Germany, Italy, and the Netherlands, maintained the old rate of
exchange between gold and currency. Other countries, such as Denmark, Fin-
land, Norway, Sweden, and the United Kingdom, reduced the amount of gold
they would pay for each unit of currency by about 50 percent. By reducing the
gold content of their currencies, these governments devalued their currencies
relative to those of other countries.
The subsequent experience of these two groups of countries conforms to the
prediction of the Mundell–Fleming model.Those countries that pursued a pol-
icy of devaluation recovered quickly from the Depression.The lower value of the
currency raised the money supply, stimulated exports, and expanded production.
By contrast, those countries that maintained the old exchange rate suffered
longer with a depressed level of economic activity.
3
3
Barry Eichengreen and Jeffrey Sachs,“Exchange Rates and Economic Recovery in the 1930s,”
Journal of Economic History 45 (December 1985): 925–946.
Trade Policy
Suppose that the government reduces imports by imposing an import quota or a
tariff.This policy shifts the net-exports schedule to the right and thus shifts the
IS* curve to the right, as in Figure 12-10. The shift in the IS* curve tends to
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raise the exchange rate.To keep the exchange rate at the fixed level, the money
supply must rise, shifting the LM* curve to the right.
The result of a trade restriction under a fixed exchange rate is very different
from that under a floating exchange rate. In both cases, a trade restriction shifts
the net-exports schedule to the right, but only under a fixed exchange rate does
a trade restriction increase net exports NX.The reason is that a trade restriction
under a fixed exchange rate induces monetary expansion rather than an appreci-
ation of the exchange rate.The monetary expansion, in turn, raises aggregate in-
come. Recall the accounting identity
NX = S ? I.
When income rises, saving also rises, and this implies an increase in net exports.
Policy in the Mundell–Fleming Model: A Summary
The Mundell–Fleming model shows that the effect of almost any economic pol-
icy on a small open economy depends on whether the exchange rate is floating
or fixed. Table 12-1 summarizes our analysis of the short-run effects of fiscal,
monetary, and trade policies on income, the exchange rate, and the trade balance.
What is most striking is that all of the results are different under floating and
fixed exchange rates.
To be more specific, the Mundell–Fleming model shows that the power of
monetary and fiscal policy to influence aggregate income depends on the
exchange-rate regime. Under floating exchange rates, only monetary policy can
affect income.The usual expansionary impact of fiscal policy is offset by a rise in
326 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-10
Exchange rate, e
Income, output, Y
1. With
a fixed
exchange
rate, . . .
2. . . . a trade
restriction shifts
the IS* curve
to the right, ...
3. . . . which
induces a shift
in the LM* curve . . .
IS*
1
IS*
2
LM*
2
LM*
1
Y
2
Y
1
4. . . . and
raises income.
A Trade Restriction Under
Fixed Exchange Rates A
tariff or an import quota
shifts the IS* curve to the
right. This induces an
increase in the money supply
to maintain the fixed
exchange rate. Hence,
aggregate income increases.
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the value of the currency. Under fixed exchange rates, only fiscal policy can af-
fect income.The normal potency of monetary policy is lost because the money
supply is dedicated to maintaining the exchange rate at the announced level.
12-4 Interest-Rate Differentials
So far, our analysis has assumed that the interest rate in a small open economy is
equal to the world interest rate: r = r*.To some extent, however, interest rates dif-
fer around the world.We now extend our analysis by considering the causes and
effects of international interest-rate differentials.
Country Risk and Exchange-Rate Expectations
When we assumed earlier that the interest rate in our small open economy is de-
termined by the world interest rate, we were applying the law of one price.We rea-
soned that if the domestic interest rate were above the world interest rate, people
from abroad would lend to that country, driving the domestic interest rate down.
And if the domestic interest rate were below the world interest rate, domestic resi-
dents would lend abroad to earn a higher return, driving the domestic interest rate
up. In the end, the domestic interest rate would equal the world interest rate.
Why doesn’t this logic always apply? There are two reasons.
One reason is country risk. When investors buy U.S. government bonds or
make loans to U.S. corporations, they are fairly confident that they will be repaid
with interest. By contrast, in some less developed countries, it is plausible to fear
that a revolution or other political upheaval might lead to a default on loan re-
payments. Borrowers in such countries often have to pay higher interest rates to
compensate lenders for this risk.
CHAPTER 12 Aggregate Demand in the Open Economy | 327
EXCHANGE-RATE REGIME
FLOATING FIXED
IMPACT ON:
Policy Ye NXYeNX
Fiscal expansion 0 ↑↓↑00
Monetary expansion ↑↓ ↑ 00 0
Import restriction 0 ↑ 0 ↑ 0 ↑
Note: This table shows the direction of impact of various economic policies on income Y, the
exchange rate e, and the trade balance NX. A “↑” indicates that the variable increases; a “↓”
indicates that it decreases; a “0’’ indicates no effect. Remember that the exchange rate is
defined as the amount of foreign currency per unit of domestic currency (for example, 100 yen
per dollar).
The Mundell–Fleming Model: Summary of Policy Effects
table 12-1
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Another reason interest rates differ across countries is expected changes in the
exchange rate. For example, suppose that people expect the French franc to fall
in value relative to the U.S. dollar.Then loans made in francs will be repaid in a
less valuable currency than loans made in dollars. To compensate for this ex-
pected fall in the French currency, the interest rate in France will be higher than
the interest rate in the United States.
Thus, because of both country risk and expectations of future exchange-rate
changes, the interest rate of a small open economy can differ from interest rates
in other economies around the world. Let’s now see how this fact affects our
analysis.
Differentials in the Mundell–Fleming Model
To incorporate interest-rate differentials into the Mundell–Fleming model, we
assume that the interest rate in our small open economy is determined by the
world interest rate plus a risk premium
v
:
r = r* +
v
.
The risk premium is determined by the perceived political risk of making loans
in a country and the expected change in the real exchange rate. For our purposes
here, we can take the risk premium as exogenous in order to examine how
changes in the risk premium affect the economy.
The model is largely the same as before.The two equations are
Y = C(Y ? T ) + I(r* +
v
) + G + NX(e) IS*,
M/P = L(r* +
v
, Y ) LM*.
For any given fiscal policy, monetary policy, price level, and risk premium,
these two equations determine the level of income and exchange rate that
equilibrate the goods market and the money market. Holding constant the
risk premium, the tools of monetary, fiscal, and trade policy work as we have
already seen.
Now suppose that political turmoil causes the country’s risk premium
v
to
rise.The most direct effect is that the domestic interest rate r rises.The higher in-
terest rate, in turn, has two effects. First, the IS* curve shifts to the left, because
the higher interest rate reduces investment. Second, the LM* curve shifts to the
right, because the higher interest rate reduces the demand for money, and this al-
lows a higher level of income for any given money supply. [Recall that Y must
satisfy the equation M/P = L(r* +
v
, Y ).] As Figure 12-11 shows, these two shifts
cause income to rise and the currency to depreciate.
This analysis has an important implication: expectations of the exchange rate
are partially self-fulfilling. For example, suppose that people come to believe that
the French franc will not be valuable in the future. Investors will place a larger
risk premium on French assets:
v
will rise in France.This expectation will drive
328 | PART IV Business Cycle Theory: The Economy in the Short Run
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up French interest rates and, as we have just seen, will drive down the value of
the French currency. Thus, the expectation that a currency will lose value in the future
causes it to lose value today.
One surprising—and perhaps inaccurate—prediction of this analysis is that an
increase in country risk as measured by
v
will cause the economy’s income to in-
crease. This occurs in Figure 12-11 because of the rightward shift in the LM*
curve.Although higher interest rates depress investment, the depreciation of the
currency stimulates net exports by an even greater amount.As a result, aggregate
income rises.
There are three reasons why, in practice, such a boom in income does not
occur. First, the central bank might want to avoid the large depreciation of the
domestic currency and, therefore, may respond by decreasing the money sup-
ply M. Second, the depreciation of the domestic currency may suddenly in-
crease the price of imported goods, causing an increase in the price level P.
Third, when some event increases the country risk premium
v
, residents of the
country might respond to the same event by increasing their demand for
money (for any given income and interest rate), because money is often the
safest asset available. All three of these changes would tend to shift the LM*
curve toward the left, which mitigates the fall in the exchange rate but also
tends to depress income.
Thus, increases in country risk are not desirable. In the short run, they typi-
cally lead to a depreciating currency and, through the three channels just de-
scribed, falling aggregate income. In addition, because a higher interest rate
reduces investment, the long-run implication is reduced capital accumulation
and lower economic growth.
CHAPTER 12 Aggregate Demand in the Open Economy | 329
figure 12-11
Exchange rate, e
Income, output, Y
3. . . . resulting
in a depreciation.
1. When an increase
in the risk premium
drives up the interest
rate, the IS* curve
shifts to the left . . .
2. . . . and the
LM* curve shifts
to the right, ...
IS*
2
IS*
1
LM*
2
LM*
1
An Increase in the Risk
Premium An increase in the
risk premium associated with
a country drives up its
interest rate. Because the
higher interest rate reduces
investment, the IS* curve
shifts to the left. Because it
also reduces money demand,
the LM* curve shifts to the
right. Income rises, and the
exchange rate depreciates.
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330 | PART IV Business Cycle Theory: The Economy in the Short Run
CASE STUDY
International Financial Crisis: Mexico 1994–1995
In August 1994, a Mexican peso was worth 30 cents. A year later, it was worth
only 16 cents.What explains this massive fall in the value of the Mexican cur-
rency? Country risk is a large part of the story.
At the beginning of 1994, Mexico was a country on the rise.The recent pas-
sage of the North American Free Trade Agreement (NAFTA), which reduced
trade barriers among the United States, Canada, and Mexico, made many confi-
dent about the future of the Mexican economy. Investors around the world were
eager to make loans to the Mexican government and to Mexican corporations.
Political developments soon changed that perception. A violent uprising in
the Chiapas region of Mexico made the political situation in Mexico seem pre-
carious.Then Luis Donaldo Colosio, the leading presidential candidate, was assas-
sinated. The political future looked less certain, and many investors started
placing a larger risk premium on Mexican assets.
At first, the rising risk premium did not affect the value of the peso, because
Mexico was operating with a fixed exchange rate.As we have seen, under a fixed
exchange rate, the central bank agrees to trade the domestic currency (pesos) for
a foreign currency (dollars) at a predetermined rate.Thus, when an increase in
the country risk premium put downward pressure on the value of the peso, the
Mexican central bank had to accept pesos and pay out dollars. This automatic
exchange-market intervention contracted the Mexican money supply (shifting
the LM* curve to the left) when the currency might otherwise have depreciated.
Yet Mexico’s reserves of foreign currency were too small to maintain its fixed
exchange rate. When Mexico ran out of dollars at the end of 1994, the Mexican
government announced a devaluation of the peso. This decision had repercus-
sions, however, because the government had repeatedly promised that it would
not devalue. Investors became even more distrustful of Mexican policymakers
and feared further Mexican devaluations.
Investors around the world (including those in Mexico) avoided buying Mex-
ican assets. The country risk premium rose once again, adding to the upward
pressure on interest rates and the downward pressure on the peso.The Mexican
stock market plummeted. When the Mexican government needed to roll over
some of its debt that was coming due, investors were unwilling to buy the new
debt. Default appeared to be the government’s only option. In just a few months,
Mexico had gone from being a promising emerging economy to being a risky
economy with a government on the verge of bankruptcy.
Then the United States stepped in.The U.S. government had three motives: to
help its neighbor to the south, to prevent the massive illegal immigration that
might follow government default and economic collapse, and to prevent the in-
vestor pessimism regarding Mexico from spreading to other developing coun-
tries. The U.S. government, together with the International Monetary Fund
(IMF), led an international effort to bail out the Mexican government. In partic-
ular, the United States provided loan guarantees for Mexican government debt,
which allowed the Mexican government to refinance the debt that was coming
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CHAPTER 12 Aggregate Demand in the Open Economy | 331
due.These loan guarantees helped restore confidence in the Mexican economy,
thereby reducing to some extent the country risk premium.
Although the U.S. loan guarantees may well have stopped a bad situation from
getting worse, they did not prevent the Mexican meltdown of 1994–1995 from
being a painful experience for the Mexican people. Not only did the Mexican
currency lose much of its value, but Mexico also went through a deep recession.
Fortunately, by the late 1990s, aggregate income was growing again, and the
worst appeared to be over. But the lesson from this experience is clear and could
well apply again in the future: changes in perceived country risk, often attribut-
able to political instability, are an important determinant of interest rates and ex-
change rates in small open economies.
CASE STUDY
International Financial Crisis: Asia 1997–1998
In 1997, as the Mexican economy was recovering from its financial crisis, a similar
story started to unfold in several Asian economies, including Thailand, South Korea,
and especially Indonesia. The symptoms were familiar: high interest rates, falling
asset values,and a depreciating currency.In Indonesia,for instance,short-term nom-
inal interest rates rose above 50 percent, the stock market lost about 90 percent of its
value (measured in U.S. dollars), and the rupiah fell against the dollar by more than
80 percent.The crisis led to rising inflation in these countries (because the depreci-
ating currency made imports more expensive) and to falling GDP (because high in-
terest rates and reduced confidence depressed spending).Real GDP in Indonesia fell
about 13 percent in 1998, making the downturn larger than any U.S. recession since
the Great Depression of the 1930s.
What sparked this firestorm? The problem began in the Asian banking systems.
For many years, the governments in the Asian nations had been more involved in
managing the allocation of resources—in particular, financial resources—than is
true in the United States and other developed countries. Some commentators had
applauded this “partnership” between government and private enterprise and had
even suggested that the United States should follow the example. Over time,
however,it became clear that many Asian banks had been extending loans to those
with the most political clout rather than to those with the most profitable invest-
ment projects. Once rising default rates started to expose this “crony capitalism,”
as it was then called, international investors started to lose confidence in the future
of these economies.The risk premiums for Asian assets rose, causing interest rates
to skyrocket and currencies to collapse.
International crises of confidence often involve a vicious circle that can am-
plify the problem. Here is one story about what happened in Asia:
1. Problems in the banking system eroded international confidence in these
economies.
2. Loss of confidence raised risk premiums and interest rates.
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12-5 Should Exchange Rates Be Floating
or Fixed?
Having analyzed how an economy works under floating and fixed exchange
rates, let’s consider which exchange-rate regime is better.
Pros and Cons of Different Exchange-Rate Systems
The primary argument for a floating exchange rate is that it allows monetary pol-
icy to be used for other purposes. Under fixed rates, monetary policy is commit-
ted to the single goal of maintaining the exchange rate at its announced level.Yet
the exchange rate is only one of many macroeconomic variables that monetary
policy can influence.A system of floating exchange rates leaves monetary policy-
makers free to pursue other goals, such as stabilizing employment or prices.
Advocates of fixed exchange rates argue that exchange-rate uncertainty makes
international trade more difficult.After the world abandoned the Bretton Woods
system of fixed exchange rates in the early 1970s, both real and nominal exchange
rates became (and remained) much more volatile than anyone had expected.
Some economists attribute this volatility to irrational and destabilizing specula-
tion by international investors. Business executives often claim that this volatility
is harmful because it increases the uncertainty that accompanies international
business transactions. Yet, despite this exchange-rate volatility, the amount of
world trade has continued to rise under floating exchange rates.
332 | PART IV Business Cycle Theory: The Economy in the Short Run
3. Rising interest rates, together with the loss of confidence, depressed the prices
of stock and other assets.
4. Falling asset prices reduced the value of collateral being used for bank loans.
5. Reduced collateral increased default rates on bank loans.
6. Greater defaults exacerbated problems in the banking system. Now return to
step 1 to complete and continue the circle.
Some economists have used this vicious-circle argument to suggest that the
Asian crisis was a self-fulfilling prophecy: bad things happened merely because
people expected bad things to happen. Most economists, however, thought the
political corruption of the banking system was a real problem, which was then
compounded by this vicious circle of reduced confidence.
As the Asian crisis developed, the IMF and the United States tried to restore
confidence, much as they had with Mexico a few years earlier. In particular, the
IMF made loans to the Asian countries to help them over the crisis; in exchange
for these loans, it exacted promises that the governments would reform their
banking systems and eliminate crony capitalism. The IMF’s hope was that the
short-term loans and longer-term reforms would restore confidence, lower the
risk premium, and turn the vicious circle into a virtuous circle.This policy seems
to have worked: the Asian economies recovered quickly from their crisis.
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Advocates of fixed exchange rates sometimes
argue that a commitment to a fixed exchange rate
is one way to discipline a nation’s monetary au-
thority and prevent excessive growth in the
money supply. Yet there are many other policy
rules to which the central bank could be com-
mitted. In Chapter 14, for instance, we discuss
policy rules such as targets for nominal GDP or
the inflation rate. Fixing the exchange rate has the
advantage of being simpler to implement than
these other policy rules, because the money sup-
ply adjusts automatically, but this policy may lead
to greater volatility in income and employment.
In the end, the choice between floating and
fixed rates is not as stark as it may seem at first.
During periods of fixed exchange rates,countries
can change the value of their currency if main-
taining the exchange rate conflicts too severely
with other goals. During periods of floating ex-
change rates, countries often use formal or infor-
mal targets for the exchange rate when deciding whether to expand or contract
the money supply.We rarely observe exchange rates that are completely fixed or
completely floating. Instead, under both systems, stability of the exchange rate is
usually one among many of the central bank’s objectives.
CHAPTER 12 Aggregate Demand in the Open Economy | 333
“Then it’s agreed. Until the dollar firms up, we let the
clamshell float.”
? The New Y
o
r
k
er collection 1971 Ed Fisher fr
om car
toonbank
.com. All Rights Reser
ved.
CASE STUDY
Monetary Union in the United States and Europe
If you have ever driven the 3,000 miles from New York City to San Francisco, you
may recall that you never needed to change your money from one form of currency
to another. In all fifty U.S. states, local residents are happy to accept the U.S. dollar
for the items you buy. Such a monetary union is the most extreme form of a fixed ex-
change rate.The exchange rate between New York dollars and San Francisco dollars
is so irrevocably fixed that you may not even know that there is a difference be-
tween the two. (What’s the difference? Each dollar bill is issued by one of the dozen
local Federal Reserve Banks.Although the bank of origin can be identified from the
bill’s markings, you don’t care which type of dollar you hold because everyone else,
including the Federal Reserve system, is ready to trade them one for one.)
If you have ever made a similar 3,000-mile trip across Europe,however,your ex-
perience was probably very different.You didn’t have to travel far before needing to
exchange your French francs for German marks, Dutch guilders, Spanish pesetas,
or Italian lira.The large number of currencies in Europe made traveling less conve-
nient and more expensive. Every time you crossed a border, you had to wait in line
at a bank to get the local money, and you had to pay the bank a fee for the service.
Recently, however, this has started to change. Many countries in Europe have
decided to form their own monetary union and use a common currency called
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Speculative Attacks, Currency Boards, and Dollarization
Imagine that you are a central banker of a small country.You and your fellow
policymakers decide to fix your currency—let’s call it the peso—against the U.S.
dollar. From now on, one peso will sell for one dollar.
As we discussed earlier, you now have to stand ready to buy and sell pesos for
a dollar each.The money supply will adjust automatically to make the equilib-
rium exchange rate equal your target.There is, however, one potential problem
with this plan: you might run out of dollars. If people come to the central bank
334 | PART IV Business Cycle Theory: The Economy in the Short Run
the euro, which was introduced in January 1999.The adoption of the euro is an
extension of the European Monetary System (EMS), which during the previous
two decades had attempted to limit exchange-rate fluctuations among participat-
ing countries.When the euro is fully adopted, this goal will be achieved: the ex-
change rate between France and Germany will be as fixed as the exchange rate
between New York City and San Francisco.
The introduction of a common currency has its costs.The most important is
that the nations of Europe will no longer be able to conduct their own monetary
policies. Instead, a European central bank, with participation of all member
countries, will set a single monetary policy for all of Europe.The central banks of
the individual countries will play a role similar to that of regional Federal Re-
serve Banks: they will monitor local conditions but they will have no control
over the money supply or interest rates. Critics of the move toward a common
currency argue that the cost of losing national monetary policy is large. If a re-
cession hits one country but not others in Europe, that country may wish it had
the tool of monetary policy to combat the downturn.
Why, according to these economists, is monetary union a bad idea for Europe if
it works so well in the United States? These economists argue that the United States
is different from Europe in two important ways. First, labor is more mobile among
U.S. states than among European countries.This is in part because the United States
has a common language and in part because most Americans are descended from
immigrants, who have shown a willingness to move.Therefore, when a regional re-
cession occurs, U.S. workers are more likely to move from high-unemployment
states to low-unemployment states. Second, the United States has a strong central
government that can use fiscal policy—such as the federal income tax—to redistrib-
ute resources among regions. Because Europe does not have these two advantages, it
will suffer more when it restricts itself to a single monetary policy.
Advocates of a common currency believe that the loss of national monetary
policy is more than offset by other gains.With a single currency in all of Europe,
travelers and businesses will no longer need to worry about exchange rates, and
this should encourage more international trade. In addition, a common currency
may have the political advantage of making Europeans feel more connected to
one another. The twentieth century was marked by two world wars, both of
which were sparked by European discord. If a common currency makes the na-
tions of Europe more harmonious, it will benefit the entire world.
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to sell large quantities of pesos, the central bank’s dollar reserves might dwindle
to zero. In this case, the central bank has no choice but to abandon the fixed ex-
change rate and let the peso depreciate.
This fact raises the possibility of a speculative attack—a change in investors’ per-
ceptions that makes the fixed exchange rate untenable. Suppose that, for no good
reason, a rumor spreads that the central bank is going to abandon the exchange-
rate peg. People would respond by rushing to the central bank to convert pesos
into dollars before the pesos lose value.This rush would drain the central bank’s
reserves and could force the central bank to abandon the peg. In this case, the
rumor would prove self-fulfilling.
To avoid this possibility, some economists argue that a fixed exchange rate
should be supported by a currency board,such as that used by Argentina in the 1990s.
A currency board is an arrangement by which the central bank holds enough for-
eign currency to back each unit of the domestic currency.In our example,the cen-
tral bank would hold one U.S. dollar (or one dollar invested in a U.S. government
bond) for every peso. No matter how many pesos turned up at the central bank to
be exchanged, the central bank would never run out of dollars.
Once a central bank has adopted a currency board, it might consider the natural
next step: it can abandon the peso altogether and let its country use the U.S. dollar.
Such a plan is called dollarization.It happens on its own in high-inflation economies,
where foreign currencies offer a more reliable store of value than the domestic
currency. But it can also occur as a matter of public policy: Panama is an example. If
a country really wants its currency to be irrevocably fixed to the dollar, the most
reliable method is to make its currency the dollar.The only loss from dollarization is
the small seigniorage revenue, which accrues to the U.S. government.
4
12-6 The Mundell–Fleming Model With a
Changing Price Level
So far we have been using the Mundell–Fleming model to study the small open
economy in the short run when the price level is fixed.To see how this model
relates to models we have examined previously, let’s consider what happens when
the price level changes.
To examine price adjustment in an open economy, we must distinguish be-
tween the nominal exchange rate e and the real exchange rate
e
, which equals
eP/P*.We can write the Mundell–Fleming model as
Y = C(Y ? T ) + I(r*) + G + NX(
e
) IS*,
M/P = L(r*, Y ) LM*.
CHAPTER 12 Aggregate Demand in the Open Economy | 335
4
Dollarization may also lead to a loss in national pride from seeing American portraits on the cur-
rency. If it wanted, the U.S. government could fix this problem by leaving blank the center space
that now has George Washington’s portrait. Each nation using the U.S. dollar could insert the face
of its own local hero.
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336 | PART IV Business Cycle Theory: The Economy in the Short Run
These equations should be familiar by now.The first equation describes the IS*
curve, and the second equation describes the LM* curve. Note that net exports
depend on the real exchange rate.
Figure 12-12 shows what happens when the price level falls. Because a lower
price level raises the level of real money balances, the LM* curve shifts to the
right, as in panel (a) of Figure 12-12.The real exchange rate depreciates, and the
equilibrium level of income rises.The aggregate demand curve summarizes this
negative relationship between the price level and the level of income, as shown
in panel (b) of Figure 12-12.
Thus, just as the IS–LM model explains the aggregate demand curve in a
closed economy, the Mundell–Fleming model explains the aggregate demand
curve for a small open economy. In both cases, the aggregate demand curve
shows the set of equilibria that arise as the price level varies.And in both cases,
anything that changes the equilibrium for a given price level shifts the aggregate
demand curve. Policies that raise income shift the aggregate demand curve to the
right; policies that lower income shift the aggregate demand curve to the left.
figure 12-12
Real exchange
rate, e
Price level, P
2. . . .
lowering
the real
exchange
rate . . .
3. . . . and
raising
income Y.
(a) The Mundell–Fleming Model
(b) The Aggregate Demand Curve
4. The AD curve
summarizes the
relationship
between P and Y.
LM*(P
1
)
IS*
LM*(P
2
)
Y
1
Y
2
Y
1
Y
2
1. A fall in the price
level P shifts the LM*
curve to the right, ...
P
1
P
2
e
1
e
2
AD
Income, output, Y
Income, output, Y
Mundell–Fleming as a Theory
of Aggregate Demand Panel
(a) shows that when the price
level falls, the LM* curve shifts
to the right. The equilibrium
level of income rises. Panel
(b) shows that this negative
relationship between P and Y
is summarized by the aggregate
demand curve.
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We can use this diagram to show how the short-run model in this chapter is re-
lated to the long-run model in Chapter 5. Figure 12-13 shows the short-run and
long-run equilibria. In both panels of the figure, point K describes the short-run
equilibrium, because it assumes a fixed price level.At this equilibrium, the demand
for goods and services is too low to keep the economy producing at its natural rate.
Over time,low demand causes the price level to fall.The fall in the price level raises
real money balances, shifting the LM* curve to the right.The real exchange rate
depreciates, so net exports rise. Eventually, the economy reaches point C, the long-
run equilibrium. The speed of transition between the short-run and long-run
equilibria depends on how quickly the price level adjusts to restore the economy
to the natural rate.
CHAPTER 12 Aggregate Demand in the Open Economy | 337
figure 12-13
Real exchange
rate, e
Price level, P
Income, output, Y
Income, output, Y
(a) The Mundell–Fleming Model
(b) The Model of Aggregate Supply
and Aggregate Demand
Y
e
1
e
2
IS*
LM*(P
2
)LM*(P
1
)
Y
1
K
C
Y
P
1
P
2
AD
SRAS
1
SRAS
2
LRAS
K
C
The Short-Run and Long-Run
Equilibria in a Small Open
Economy Point K in both panels
shows the equilibrium under the
Keynesian assumption that the
price level is fixed at P
1
. Point C
in both panels shows the
equilibrium under the classical
assumption that the price level
adjusts to maintain income at
its natural rate Y
?
.
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The levels of income at point K and point C are both of interest. Our central
concern in this chapter has been how policy influences point K, the short-run
equilibrium. In Chapter 5 we examined the determinants of point C, the long-
run equilibrium. Whenever policymakers consider any change in policy, they
need to consider both the short-run and long-run effects of their decision.
12-7 A Concluding Reminder
In this chapter we have examined how a small open economy works in the short
run when prices are sticky.We have seen how monetary and fiscal policy influence
income and the exchange rate, and how the behavior of the economy depends on
whether the exchange rate is floating or fixed.In closing,it is worth repeating a les-
son from Chapter 5. Many countries, including the United States, are neither
closed economies nor small open economies: they lie somewhere in between.
A large open economy, such as the United States, combines the behavior of a
closed economy and the behavior of a small open economy.When analyzing poli-
cies in a large open economy, we need to consider both the closed-economy logic
of Chapter 11 and the open-economy logic developed in this chapter.The appendix
to this chapter presents a model for a large open economy.The results of that model
are, as one would guess, a mixture of the two polar cases we have already examined.
To see how we can draw on the logic of both the closed and small open
economies and apply these insights to the United States, consider how a mone-
tary contraction affects the economy in the short run. In a closed economy, a
monetary contraction raises the interest rate, lowers investment, and thus lowers
aggregate income. In a small open economy with a floating exchange rate, a
monetary contraction raises the exchange rate, lowers net exports, and thus low-
ers aggregate income.The interest rate is unaffected, however, because it is deter-
mined by world financial markets.
The U.S. economy contains elements of both cases. Because the United States is
large enough to affect the world interest rate and because capital is not perfectly
mobile across countries, a monetary contraction does raise the interest rate and de-
press investment.At the same time, a monetary contraction also raises the value of
the dollar, thereby depressing net exports. Hence, although the Mundell–Fleming
model does not precisely describe an economy like that of the United States, it
does predict correctly what happens to international variables such as the exchange
rate, and it shows how international interactions alter the effects of monetary and
fiscal policies.
Summary
1. The Mundell–Fleming model is the IS–LM model for a small open economy.
It takes the price level as given and then shows what causes fluctuations in
income and the exchange rate.
2. The Mundell–Fleming model shows that fiscal policy does not influence ag-
gregate income under floating exchange rates. A fiscal expansion causes the
338 | PART IV Business Cycle Theory: The Economy in the Short Run
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currency to appreciate, reducing net exports and offsetting the usual expan-
sionary impact on aggregate income. Fiscal policy does influence aggregate
income under fixed exchange rates.
3. The Mundell–Fleming model shows that monetary policy does not influence
aggregate income under fixed exchange rates. Any attempt to expand the
money supply is futile, because the money supply must adjust to ensure that
the exchange rate stays at its announced level. Monetary policy does influ-
ence aggregate income under floating exchange rates.
4. If investors are wary of holding assets in a country, the interest rate in that
country may exceed the world interest rate by some risk premium.According
to the Mundell–Fleming model, an increase in the risk premium causes the
interest rate to rise and the currency of that country to depreciate.
5. There are advantages to both floating and fixed exchange rates. Floating ex-
change rates leave monetary policymakers free to pursue objectives other than
exchange-rate stability. Fixed exchange rates reduce some of the uncertainty
in international business transactions.
CHAPTER 12 Aggregate Demand in the Open Economy | 339
1. In the Mundell–Fleming model with floating
exchange rates, explain what happens to aggre-
gate income, the exchange rate, and the trade
balance when taxes are raised.What would hap-
pen if exchange rates were fixed rather than
floating?
2. In the Mundell–Fleming model with floating ex-
change rates, explain what happens to aggregate
income, the exchange rate, and the trade balance
when the money supply is reduced.What would
KEY CONCEPTS
Mundell–Fleming model
Floating exchange rates
QUESTIONS FOR REVIEW
Fixed exchange rates
Devaluation
Revaluation
happen if exchange rates were fixed rather than
floating?
3. In the Mundell–Fleming model with floating ex-
change rates, explain what happens to aggregate
income, the exchange rate, and the trade balance
when a quota on imported cars is removed.What
would happen if exchange rates were fixed rather
than floating?
4. What are the advantages of floating exchange
rates and fixed exchange rates?
PROBLEMS AND APPLICATIONS
1. Use the Mundell–Fleming model to predict what
would happen to aggregate income, the exchange
rate, and the trade balance under both floating
and fixed exchange rates in response to each of
the following shocks:
a. A fall in consumer confidence about the future
induces consumers to spend less and save more.
b. The introduction of a stylish line of Toyotas
makes some consumers prefer foreign cars over
domestic cars.
c. The introduction of automatic teller machines
reduces the demand for money.
2. The Mundell–Fleming model takes the world
interest rate r* as an exogenous variable. Let’s
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340 | PART IV Business Cycle Theory: The Economy in the Short Run
consider what happens when this variable
changes.
a. What might cause the world interest rate to rise?
b. In the Mundell–Fleming model with a floating
exchange rate, what happens to aggregate in-
come, the exchange rate, and the trade balance
when the world interest rate rises?
c. In the Mundell–Fleming model with a fixed
exchange rate, what happens to aggregate in-
come, the exchange rate, and the trade balance
when the world interest rate rises?
3. Business executives and policymakers are often
concerned about the “competitiveness’’ of Ameri-
can industry (the ability of U.S. industries to sell
their goods profitably in world markets).
a. How would a change in the exchange rate af-
fect competitiveness?
b. Suppose you wanted to make domestic indus-
tries more competitive but did not want to alter
aggregate income. According to the Mundell–
Fleming model, what combination of mone-
tary and fiscal policies should you pursue?
4. Suppose that higher income implies higher im-
ports and thus lower net exports.That is, the net-
exports function is
NX = NX(e, Y ).
Examine the effects in a small open economy of a
fiscal expansion on income and the trade balance
under
a. A floating exchange rate.
b. A fixed exchange rate.
How does your answer compare to the results in
Table 12-1?
5. Suppose that money demand depends on dispos-
able income, so that the equation for the money
market becomes
M/P = L(r, Y ? T ).
Analyze the impact of a tax cut in a small open
economy on the exchange rate and income under
both floating and fixed exchange rates.
6. Suppose that the price level relevant for money
demand includes the price of imported goods and
that the price of imported goods depends on the
exchange rate. That is, the money market is de-
scribed by
M/P = L(r, Y ),
where
P = lP
d
+ (1 ? l)P
f
/e.
The parameter l is the share of domestic goods in
the price index P. Assume that the price of do-
mestic goods P
d
and the price of foreign goods
measured in foreign currency P
f
are fixed.
a. Suppose we graph the LM* curve for given
values of P
d
and P
f
(instead of the usual P).
Explain why in this model this LM* curve is
upward sloping rather than vertical.
b. What is the effect of expansionary fiscal policy
under floating exchange rates in this model?
Explain. Contrast with the standard Mundell–
Fleming model.
c. Suppose that political instability increases the
country risk premium and, thereby, the interest
rate.What is the effect on the exchange rate,the
price level, and aggregate income in this
model? Contrast with the standard Mundell–
Fleming model.
7. Use the Mundell–Fleming model to answer the
following questions about the state of California
(a small open economy).
a. If California suffers from a recession, should
the state government use monetary or fiscal
policy to stimulate employment? Explain.
(Note: For this question, assume that the state
government can print dollar bills.)
b. If California prohibited the import of wines
from the state of Washington, what would hap-
pen to income, the exchange rate, and the
trade balance? Consider both the short-run
and the long-run impacts.
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CHAPTER 12 Aggregate Demand in the Open Economy | 341
When analyzing policies in an economy such as the United States, we need to
combine the closed-economy logic of the IS–LM model and the small-open-
economy logic of the Mundell–Fleming model.This appendix presents a model
for the intermediate case of a large open economy.
As we discussed in the appendix to Chapter 5, a large open economy differs
from a small open economy because its interest rate is not fixed by world fi-
nancial markets. In a large open economy, we must consider the relationship
between the interest rate and the flow of capital abroad.The net capital out-
flow is the amount that domestic investors lend abroad minus the amount that
foreign investors lend here. As the domestic interest rate falls, domestic in-
vestors find foreign lending more attractive, and foreign investors find lending
here less attractive.Thus, the net capital outflow is negatively related to the in-
terest rate. Here we add this relationship to our short-run model of national
income.
The three equations of the model are
Y = C(Y ? T ) + I(r) + G + NX(e),
M/P = L(r, Y ),
NX(e) = CF(r).
The first two equations are the same as those used in the Mundell–Fleming
model of this chapter.The third equation, taken from the appendix to Chapter 5,
states that the trade balance NX equals the net capital outflow CF, which in turn
depends on the domestic interest rate.
To see what this model implies, substitute the third equation into the first, so
the model becomes
Y = C(Y ? T ) + I(r) + G + CF(r) IS,
M/P = L(r, Y ) LM.
These two equations are much like the two equations of the closed-economy
IS–LM model.The only difference is that expenditure now depends on the in-
terest rate for two reasons. As before, a higher interest rate reduces investment.
But now, a higher interest rate also reduces the net capital outflow and thus
lowers net exports.
To analyze this model, we can use the three graphs in Figure 12-14 on page
342. Panel (a) shows the IS–LM diagram. As in the closed-economy model in
Chapters 10 and 11, the interest rate r is on the vertical axis, and income Y is on
the horizontal axis.The IS and LM curves together determine the equilibrium
level of income and the equilibrium interest rate.
A Short-Run Model of the Large Open Economy
APPENDIX
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The new net-capital-outflow term in the IS equation, CF(r), makes this
IS curve flatter than it would be in a closed economy.The more responsive in-
ternational capital flows are to the interest rate, the flatter the IS curve is.You
might recall from the Chapter 5 appendix that the small open economy repre-
sents the extreme case in which the net capital outflow is infinitely elastic at
the world interest rate. In this extreme case, the IS curve is completely flat.
Hence, a small open economy would be depicted in this figure with a hori-
zontal IS curve.
Panels (b) and (c) show how the equilibrium from the IS–LM model deter-
mines the net capital outflow, the trade balance, and the exchange rate. In panel
(b) we see that the interest rate determines the net capital outflow. This curve
slopes downward because a higher interest rate discourages domestic investors
from lending abroad and encourages foreign investors to lend here. In panel (c)
we see that the exchange rate adjusts to ensure that net exports of goods and ser-
vices equal the net capital outflow.
Now let’s use this model to examine the impact of various policies.We assume
that the economy has a floating exchange rate, because this assumption is correct
for most large open economies such as the United States.
342 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-14
Real interest
rate, r
Exchange rate, e
Income, output, Y Net capital
outflow, CF
Net exports, NX
Y
1
IS
LM
r
1
CF
1
NX
1
r
r
1
CF(r)
e
1
NX(e)
CF
(a) The IS–LM Model (b) Net Capital Outflow
(c) The Market for Foreign Exchange
A Short-Run Model of a Large
Open Economy Panel (a) shows
that the IS and LM curves
determine the interest rate r
1
and
income Y
1
. Panel (b) shows that
r
1
determines the net capital
outflow CF
1
. Panel (c) shows that
CF
1
and the net-exports schedule
determine the exchange rate e
1
.
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Fiscal Policy
Figure 12-15 examines the impact of a fiscal expansion.An increase in govern-
ment purchases or a cut in taxes shifts the IS curve to the right.As panel (a) il-
lustrates, this shift in the IS curve leads to an increase in the level of income
and an increase in the interest rate.These two effects are similar to those in a
closed economy.
Yet, in the large open economy, the higher interest rate reduces the net capital
outflow, as in panel (b).The fall in the net capital outflow reduces the supply of
dollars in the market for foreign exchange.The exchange rate appreciates, as in
panel (c). Because domestic goods become more expensive relative to foreign
goods, net exports fall.
Figure 12-15 shows that a fiscal expansion does raise income in the large open
economy, unlike in a small open economy under a floating exchange rate.The
impact on income, however, is smaller than in a closed economy. In a closed
economy, the expansionary impact of fiscal policy is partially offset by the
CHAPTER 12 Aggregate Demand in the Open Economy | 343
figure 12-15
Real interest
rate, r
Exchange
rate, e
Income,
output, Y
Net capital
outflow,
CF
Net exports,
NX
Y
1
Y
2
IS
1
IS
2
LM
r
2
r
1
CF
2
CF
2
CF
1
CF
1
NX
2
NX
1
CF(r)
e
2
e
1
NX(e)
r
r
2
r
1
2. . . . raises
the interest
rate, . . .
4. . . . raises
the exchange
rate, . . .
5. . . . and
reduces net
exports.
3. . . . which
lowers net
capital
outflow, . . .
1. A fiscal
expansion . . .
(a) The IS–LM Model (b) Net Capital Outflow
(c) The Market for Foreign Exchange
A Fiscal Expansion in a Large Open
Economy Panel (a) shows that a
fiscal expansion shifts the IS curve to
the right. Income rises from Y
1
to Y
2
,
and the interest rate rises from r
1
to
r
2
. Panel (b) shows that the increase
in the interest rate causes the net
capital outflow to fall from CF
1
to
CF
2
. Panel (c) shows that the fall in
the net capital outflow reduces the
net supply of dollars, causing the
exchange rate to appreciate from
e
1
to e
2
.
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crowding out of investment: as the interest rate rises, investment falls, reducing
the fiscal-policy multipliers. In a large open economy, there is yet another offset-
ting factor: as the interest rate rises, the net capital outflow falls, the exchange rate
appreciates, and net exports fall.Together these effects are not large enough to
make fiscal policy powerless, as it is in a small open economy, but they do reduce
fiscal policy’s impact.
Monetary Policy
Figure 12-16 examines the effect of a monetary expansion. An increase in the
money supply shifts the LM curve to the right, as in panel (a).The level of in-
come rises, and the interest rate falls. Once again, these effects are similar to those
in a closed economy.
Yet, as panel (b) shows, the lower interest rate leads to a higher net capital out-
flow.The increase in CF raises the supply of dollars in the market for foreign ex-
change.The exchange rate depreciates, as in panel (c).As domestic goods become
cheaper relative to foreign goods, net exports rise.
344 | PART IV Business Cycle Theory: The Economy in the Short Run
figure 12-16
Real interest
rate, r
Exchange
rate, e
Income,
output, Y
Net capital
outflow,
CF
Net exports, NX
2. . . . lowers
the interest
rate, . . .
4. . . . lowers
the exchange
rate, . . .
1. A monetary
expansion . . .
Y
2
Y
1
IS
LM
2
LM
1
NX(e)
e
1
e
2
CF(r)
r
r
1
r
2
r
1
r
2
CF
1
CF
2
CF
2
CF
1
NX
1
NX
2
5. . . . and
raises net
exports.
3. . . . which
increases net
capital
outflow, . . .
(a) The IS–LM Model (b) Net Capital Outflow
(c) The Market for Foreign ExchangeA Monetary Expansion in a Large
Open Economy Panel (a) shows
that a monetary expansion shifts
the LM curve to the right. Income
rises from Y
1
to Y
2
, and the interest
rate falls from r
1
to r
2
. Panel (b)
shows that the decrease in the
interest rate causes the net capital
outflow to increase from CF
1
to CF
2
.
Panel (c) shows that the increase in
the net capital outflow raises the
net supply of dollars, which causes
the exchange rate to depreciate
from e
1
to e
2
.
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We can now see that the monetary transmission mechanism has two parts in a
large open economy. As in a closed economy, a monetary expansion lowers the
interest rate.As in a small open economy, a monetary expansion causes the cur-
rency to depreciate in the market for foreign exchange.The lower interest rate
stimulates investment, and the lower exchange rate stimulates net exports.
A Rule of Thumb
This model of the large open economy describes well the U.S. economy today.
Yet it is somewhat more complicated and cumbersome than the model of the
closed economy we studied in Chapters 10 and 11 and the model of the small
open economy we developed in this chapter. Fortunately, there is a useful rule
of thumb to help you determine how policies influence a large open economy
without remembering all the details of the model: The large open economy is an
average of the closed economy and the small open economy.To find how any policy will
affect any variable, find the answer in the two extreme cases and take an average.
For example, how does a monetary contraction affect the interest rate and in-
vestment in the short run? In a closed economy, the interest rate rises, and invest-
ment falls. In a small open economy, neither the interest rate nor investment
changes.The effect in the large open economy is an average of these two cases: a
monetary contraction raises the interest rate and reduces investment, but only
somewhat.The fall in the net capital outflow mitigates the rise in the interest rate
and the fall in investment that would occur in a closed economy. But unlike in a
small open economy, the international flow of capital is not so strong as to negate
fully these effects.
This rule of thumb makes the simple models all the more valuable.Although
they do not describe perfectly the world in which we live, they do provide a use-
ful guide to the effects of economic policy.
CHAPTER 12 Aggregate Demand in the Open Economy | 345
1. Imagine that you run the central bank in a large
open economy.Your goal is to stabilize income, and
you adjust the money supply accordingly. Under
your policy, what happens to the money supply, the
interest rate, the exchange rate, and the trade bal-
ance in response to each of the following shocks?
a. The president raises taxes to reduce the budget
deficit.
b. The president restricts the import of Japanese
cars.
2. Over the past several decades, investors around the
world have become more willing to take advan-
tage of opportunities in other countries. Because
MORE PROBLEMS AND APPLICATIONS
of this increasing sophistication, economies are
more open today than in the past. Consider how
this development affects the ability of monetary
policy to influence the economy.
a. If investors become more willing to substitute
foreign and domestic assets, what happens to
the slope of the CF function?
b. If the CF function changes in this way, what
happens to the slope of the IS curve?
c. How does this change in the IS curve affect
the Fed’s ability to control the interest rate?
d. How does this change in the IS curve affect
the Fed’s ability to control national income?
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346 | PART IV Business Cycle Theory: The Economy in the Short Run
3. Suppose that policymakers in a large open econ-
omy want to raise the level of investment without
changing aggregate income or the exchange rate.
a. Is there any combination of domestic monetary
and fiscal policies that would achieve this goal?
b. Is there any combination of domestic monetary,
fiscal, and trade policies that would achieve this
goal?
c. Is there any combination of monetary and fiscal
policies at home and abroad that would achieve
this goal?
4. Suppose that a large open economy has a fixed
exchange rate.
a. Describe what happens in response to a fis-
cal contraction, such as a tax increase. Com-
pare your answer to the case of a small open
economy.
b. Describe what happens if the central bank ex-
pands the money supply by buying bonds from
the public. Compare your answer to the case
of a small open economy.