Download Principles of Economics, Case and Fair,9e

Aggregate Demand
in the Goods and
Money Markets
Lecture 8
11
LECTURE OUTLINE
Planned Investment and the Interest Rate
Other Determinants of Planned Investment
Planned Aggregate Expenditure and the
Interest Rate
Equilibrium in Both the Goods and Money
Markets
Policy Effects in the Goods and Money
Markets
Expansionary Policy Effects
Contractionary Policy Effects
The Macroeconomic Policy Mix
The Aggregate Demand (AD) Curve
The Aggregate Demand Curve: A Warning
Other Reasons for a Downward-Sloping
Aggregate Demand Curve
Aggregate Expenditure and Aggregate Demand
Shifts of the Aggregate Demand Curve
Looking Ahead: Determining the Price
Level
Appendix: The IS-LM Diagram
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Aggregate Demand in the Goods and Money Markets
goods market The market in which goods and
services are exchanged and in which the
equilibrium level of aggregate output is determined.
money market The market in which financial
instruments are exchanged and in which the
equilibrium level of the interest rate is determined.
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Planned Investment and the Interest Rate
 FIGURE 12.1 Planned Investment Schedule
Planned investment spending is a negative function of the interest rate.
An increase in the interest rate from 3 percent to 6 percent reduces planned investment from I0 to I1.
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Planned Investment and the Interest Rate
Other Determinants of Planned Investment
The assumption that planned investment depends
only on the interest rate is obviously a
simplification, just as is the assumption that
consumption depends only on income. In practice,
the decision of a firm on how much to invest
depends on, among other things, its expectation of
future sales.
The optimism or pessimism of entrepreneurs about
the future course of the economy can have an
important effect on current planned investment.
Keynes used the phrase animal spirits to describe
the feelings of entrepreneurs, and he argued that
these feelings affect investment decisions.
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Planned Investment and the Interest Rate
Other Determinants of Planned Investment
Interest Rates and
Investment Spending
A recent study by Simon
Gilchrist, Fabio Natalucci,
and Egon Zakrajsek finds
that interest rates have a
powerful effect on the
behavior of firms.
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Planned Investment and the Interest Rate
Planned Aggregate Expenditure and the Interest Rate
We can use the fact that planned investment
depends on the interest rate to consider how
planned aggregate expenditure (AE) depends on
the interest rate.
Recall that planned aggregate expenditure is the
sum of consumption, planned investment, and
government purchases.
AE ≡ C + I + G
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Planned Investment and the Interest Rate
Planned Aggregate Expenditure and the Interest Rate
 FIGURE 12.2 The Effect of an Interest Rate Increase on Planned Aggregate Expenditure
An increase in the interest rate from 3 percent to 6 percent lowers planned aggregate
expenditure and thus reduces equilibrium income from Y0 to Y1.
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Planned Investment and the Interest Rate
Planned Aggregate Expenditure and the Interest Rate
The effects of a change in the interest rate include:
 A high interest rate (r) discourages planned
investment (I).
 Planned investment is a part of planned
aggregate expenditure (AE).
 Thus, when the interest rate rises, planned
aggregate expenditure (AE) at every level of
income falls.
 Finally, a decrease in planned aggregate
expenditure lowers equilibrium output (income)
(Y) by a multiple of the initial decrease in planned
investment.
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Planned Investment and the Interest Rate
Planned Aggregate Expenditure and the Interest Rate
Using a convenient shorthand:
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Equilibrium in Both the Goods and Money Markets
An increase in the interest rate (r) decreases output
(Y) in the goods market because an increase in r
lowers planned investment.
When income (Y) increase, this shifts the money
demand curve to the right, which increases the
interest rate (r) with a fixed money supply. We can
thus write:
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Equilibrium in Both the Goods and Money Markets
 FIGURE 12.3 Links Between the Goods Market and the Money Market
Planned investment depends on the interest rate, and money demand depends on aggregate output.
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Policy Effects in the Goods and Money Markets
Expansionary Policy Effects
expansionary fiscal policy An increase in
government spending or a reduction in net taxes
aimed at increasing aggregate output (income) (Y).
expansionary monetary policy An increase in the
money supply aimed at increasing aggregate output
(income) (Y).
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Policy Effects in the Goods and Money Markets
Expansionary Policy Effects
Expansionary Fiscal Policy: An Increase in Government
Purchases (G) or a Decrease in Net Taxes (T)
crowding-out effect The tendency for increases in
government spending to cause reductions in private
investment spending.
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Policy Effects in the Goods and Money Markets
Expansionary Policy Effects
Expansionary Fiscal Policy: An Increase in Government
Purchases (G) or a Decrease in Net Taxes (T)
 FIGURE 12.4 The
Crowding-Out Effect
An increase in government
spending G from G0 to G1 shifts
the planned aggregate
expenditure schedule from 1 to
2.
The crowding-out effect of the
decrease in planned
investment (brought about by
the increased interest rate)
then shifts the planned
aggregate expenditure
schedule from 2 to 3.
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Policy Effects in the Goods and Money Markets
Expansionary Policy Effects
Expansionary Fiscal Policy: An Increase in Government
Purchases (G) or a Decrease in Net Taxes (T)
interest sensitivity or insensitivity of planned
investment The responsiveness of planned
investment spending to changes in the interest rate.
Interest sensitivity means that planned investment
spending changes a great deal in response to
changes in the interest rate; interest insensitivity
means little or no change in planned investment as
a result of changes in the interest rate.
Effects of an expansionary fiscal policy:
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Policy Effects in the Goods and Money Markets
Expansionary Policy Effects
Expansionary Monetary Policy: An Increase in the
Money Supply
Effects of an expansionary monetary policy:
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Policy Effects in the Goods and Money Markets
Contractionary Policy Effects
Contractionary Fiscal Policy: A Decrease in Government
Spending (G) or an Increase in Net Taxes (T)
contractionary fiscal policy A decrease in
government spending or an increase in net taxes
aimed at decreasing aggregate output (income) (Y).
Effects of a contractionary fiscal policy:
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Policy Effects in the Goods and Money Markets
Contractionary Policy Effects
Contractionary Monetary Policy: A Decrease in the
Money Supply
contractionary monetary policy A decrease in
the money supply aimed at decreasing aggregate
output (income) (Y).
Effects of a contractionary monetary policy:
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The Aggregate Demand (AD) Curve
aggregate demand The total demand for goods
and services in the economy.
aggregate demand (AD) curve A curve that
shows the negative relationship between aggregate
output (income) and the price level. Each point on
the AD curve is a point at which both the goods
market and the money market are in equilibrium.
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The Aggregate Demand (AD) Curve
 FIGURE 12.5 The Impact of an Increase in the Price Level on the Economy—Assuming No Changes
in G, T, and Ms
This figure shows that when P increases, Y decreases.
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The Aggregate Demand (AD) Curve
 FIGURE 12.6 The Aggregate Demand
(AD) Curve
At all points along the AD curve, both
the goods market and the money market
are in equilibrium. The policy variables
G, T, and Ms are fixed.
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The Aggregate Demand (AD) Curve
The Aggregate Demand Curve: A Warning
It is important that you realize what the aggregate
demand curve represents.
The aggregate demand curve is more complex than
a simple individual or market demand curve. The
AD curve is not a market demand curve, and it is
not the sum of all market demand curves in the
economy.
To understand what the aggregate demand curve
represents, you must understand the interaction
between the goods market and the money markets.
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The Aggregate Demand (AD) Curve
Other Reasons for a Downward-Sloping Aggregate Demand Curve
The Consumption Link
The consumption link provides another reason for
the AD curve’s downward slope.
An increase in the price level increases the demand
for money, which leads to an increase in the interest
rate, which leads to a decrease in consumption (as
well as planned investment), which leads to a
decrease in aggregate output (income).
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The Aggregate Demand (AD) Curve
Other Reasons for a Downward-Sloping Aggregate Demand Curve
The Consumption Link
The initial decrease in consumption (brought about
by the increase in the interest rate) contributes to
the overall decrease in output.
Planned investment does not bear all the burden of
providing the link from a higher interest rate to a
lower level of aggregate output.
Decreased consumption brought about by a higher
interest rate also contributes to this effect.
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The Aggregate Demand (AD) Curve
Other Reasons for a Downward-Sloping Aggregate Demand Curve
The Real Wealth Effect
real wealth, or real balance, effect The change in
consumption brought about by a change in real
wealth that results from a change in the price level.
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The Aggregate Demand (AD) Curve
Aggregate Expenditure and Aggregate Demand
At equilibrium, planned aggregate expenditure
(AE ≡ C + I + G) and aggregate output (Y) are
equal:
equilibrium condition: C + I + G = Y
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The Aggregate Demand (AD) Curve
Shifts of the Aggregate Demand Curve
 FIGURE 12.7 The Effect of an
Increase in Money Supply on the AD
Curve
An increase in the money supply (Ms)
causes the aggregate demand curve to
shift to the right, from AD0 to AD1. This
shift occurs because the increase in Ms
lowers the interest rate, which increases
planned investment (and thus planned
aggregate expenditure). The final result
is an increase in output at each possible
price level.
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The Aggregate Demand (AD) Curve
Shifts of the Aggregate Demand Curve
 FIGURE 12.8 The Effect of an
Increase in Government Purchases or a
Decrease in Net Taxes on the AD Curve
An increase in government purchases
(G) or a decrease in net taxes (T)
causes the aggregate demand curve to
shift to the right, from AD0 to AD1. The
increase in G increases planned
aggregate expenditure, which leads to
an increase in output at each possible
price level. A decrease in T causes
consumption to rise. The higher
consumption then increases planned
aggregate expenditure, which leads to
an increase in output at each possible
price level.
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The Aggregate Demand (AD) Curve
Shifts of the Aggregate Demand Curve
 FIGURE 12.9 Factors That Shift the Aggregate Demand Curve
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APPENDIX A
THE IS-LM DIAGRAM
THE IS CURVE
An IS curve illustrates the negative relationship
between the equilibrium value of aggregate output
(income) (Y) and the interest rate in the goods
market.
 FIGURE 12A.1 The IS Curve
Each point on the IS curve
corresponds to the equilibrium
point in the goods market for the
given interest rate.
When government spending (G)
increases, the IS curve shifts to
the right, from IS0 to IS1.
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APPENDIX A
THE IS-LM DIAGRAM
THE LM CURVE
An LM curve illustrates the positive relationship
between the equilibrium value of the interest rate
and aggregate output (income) (Y) in the money
market.
 FIGURE 12A.2 The LM Curve
Each point on the LM curve
corresponds to the equilibrium
point in the money market for the
given value of aggregate output
(income).
Money supply (Ms) increases shift
the LM curve to the right, from
LM0 to LM1.
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APPENDIX A
THE IS-LM DIAGRAM
THE IS-LM DIAGRAM
The IS-LM diagram is a way of depicting
graphically the determination of aggregate output
(income) and the interest rate in the goods and
money markets.
 FIGURE 12A.3 The IS-LM
Diagram
The point at which the IS and LM
curves intersect corresponds to
the point at which both the goods
market and the money market are
in equilibrium.
The equilibrium values of
aggregate output and the interest
rate are Y0 and r0.
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APPENDIX A
THE IS-LM DIAGRAM
THE IS-LM DIAGRAM
 FIGURE 12A.4 An Increase in Government Purchases (G)
When G increases, the IS curve shifts to the right.
This increases the equilibrium value of both Y and r.
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APPENDIX A
THE IS-LM DIAGRAM
THE IS-LM DIAGRAM
 FIGURE 12A.5 An Increase in the Money Supply (Ms)
When Ms increases, the LM curve shifts to the right.
This increases the equilibrium value of Y and decreases the equilibrium value of r.
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