Chapters 22 and 23.
where the economy gravitates to in the long run.
3
Many economists believe that
the natural rate of unemployment is currently around 6%.
C H A P T E R 2 4
Aggregate Demand and Supply Analysis
623
TA B L E 2 4 - 1
Factors That Shift the Aggregate Demand Curve
Shift in the Aggregate
Factor
Change
Demand Curve
Money supply,
M
c
Government spending,
G
c
Taxes,
T
c
Net exports,
NX
c
Consumer optimism,
C
c
Business optimism,
I
c
Note:
Only increases (
c
) in the factors are shown. The effect of decreases in the factors would be the opposite of those
indicated in the Shift column. Note that the quantity theory approach views the money supply as an important cause
of shifts in the aggregate demand curve.
P
Y
AD
2
AD
1
P
Y
AD
2
AD
1
P
Y
AD
2
AD
1
P
Y
AD
2
AD
1
P
Y
AD
2
AD
1
P
Y
AD
2
AD
1
3
A related concept is the
nonaccelerating inflation rate of unemployment (NAIRU)
, the rate of
unemployment at which there is no tendency for inflation to change.
624
PA R T V I I
Monetary Theory
The level of aggregate output produced at the natural rate of unemployment is
called the
natural rate of output
; it is where the economy settles in the long run
for any price level. Hence the long-run aggregate supply curve (
LRAS
) is vertical at
the natural rate of output, denoted by
Y
n
, as drawn in Figure 24-2.
Because wages and prices take time to adjust to economic conditions, a process
described by saying that wages and prices are
sticky
, the aggregate supply curve
(
AS
1
) in the short run is upward-sloping, as depicted in Figure 24-3. To understand
why the short-run aggregate supply curve is upward-sloping, we have to look at
the factors that cause the quantity of output supplied to change. Because the goal
of business is to maximize profits, the quantity of output supplied is determined by
the profit made on each unit of output. If profit rises, more output will be produced,
and the quantity of output supplied will increase; if it falls, less output will be pro-
duced, and the quantity of aggregate output supplied will fall.
Y
n
Aggregate Output,
Y
Aggregate
Price Level,
P
LRAS
F I G U R E 2 4 - 2
Long-Run Aggregate Supply Curve
The amount of aggregate output supplied at any given price level goes to the natural rate level of
output in the long run, so that the long-run aggregate supply curve
LRAS
is a vertical line at
Y
n
.
Short-Run
Aggregate
Supply Curve
P
1
P
2
Aggregate Price
Level,
P
A
A
*
B
B
*
AS
1
AS
2
Aggregate Output,
Y
F I G U R E 2 4 - 3
Aggregate Supply Curve in the Short Run
A rise in the costs of production shifts the short-run supply curve leftward from
AS
1
to
AS
2
.
Profit on a unit of output equals the price for the unit minus the costs of pro-
ducing it. In the short run, costs of many factors that go into producing goods and
services are fixed; wages, for example, are often fixed for periods of time by labour
contracts, and raw materials are often bought by firms under long-term contracts
that fix the price. Because these costs of production are fixed in the short run,
when the overall price level rises, the price for a unit of output will rise relative to
the costs of producing it, and the profit per unit will rise. Because the higher price
level results in higher profits in the short run, firms increase production, and the
quantity of aggregate output supplied rises, resulting in an upward-sloping short-
run aggregate supply curve.
Frequent mention of the
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