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CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 2
Real GDP Growth in the United StatesReal GDP Growth in the United States
-4
-2
0
2
4
6
8
10
1960 1965 1970 1975 1980 1985 1990 1995 2000
Percent change from 4 quarters
earlierAverage growth
rate = 3.5%
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 3
Stylized facts about business cyclesStylized facts about business cycles
No simple regular or cyclical pattern
Distributed unevenly over the components of output– stable: consumption of non-durables
and services, net export– Unstable: consumption of durables,
housing, inventories
Asymmetries between rises and falls in output– Long time slightly above and short
time far below the mean value
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 4
Chapter objectivesChapter objectives
difference between short run & long run
introduction to aggregate demand
aggregate supply in the short run & long run
see how model of aggregate supply and demand can be used to analyze short-run and long-run effects of “shocks”
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 5
Time horizonsTime horizons
Long run: Prices are flexible, respond to changes in supply or demand
Short run:many prices are “sticky” at some predetermined level
The economy behaves much differently when prices are sticky.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 6
In Classical Macroeconomic Theory,In Classical Macroeconomic Theory,
Output is determined by the supply side:– supplies of capital, labor– technology
Changes in demand for goods & services (C, I, G ) only affect prices, not quantities.
Complete price flexibility is a crucial assumption,so classical theory applies in the long run.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 7
When prices are stickyWhen prices are sticky
…output and employment also depend on demand for goods & services,which is affected by
fiscal policy (G and T )
monetary policy (M )
other factors, like exogenous changes in C or I.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 8
The model of The model of aggregate demand and supplyaggregate demand and supply
the paradigm that most mainstream economists & policymakers use to think about economic fluctuations and policies to stabilize the economy
shows how the price level and aggregate output are determined simultaneously
shows how the economy’s behavior is different in the short run and long run
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 9
Aggregate demandAggregate demand
The aggregate demand curve shows the relationship between the price level and the quantity of output demanded.
For this chapter’s intro to the AD/AS model, we use a very simple theory of aggregate demand based on the Quantity Theory of Money.
Chapters 10-12 develop the theory of aggregate demand in more detail.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 10
The Quantity Equation as Agg. DemandThe Quantity Equation as Agg. Demand
From Lecture 3, recall the quantity equationM V = P Y
and the money demand function it implies:
(M/P )d = k Ywhere V = 1/k = velocity.
For given values of M and V, these equations imply an inverse relationship between P and Y:
P = (M V) / Y
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 11
The downward-sloping The downward-sloping ADAD curve curve
An increase in the price level causes a fall in real money balances (M/P ),
causing a decrease in the demand for goods & services.
Y
P
AD
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 12
Shifting the Shifting the ADAD curve curve
An increase in the money supply shifts the AD curve to the right.
Y
P
AD1
AD2
P = (M V) / YRise in M
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 13
Aggregate Supply in the Long RunAggregate Supply in the Long Run
Recall from chapter 3: In the long run, output is determined by factor supplies and technology
, ( )Y F K L
is the full-employment or natural level of output, the level of output at which the economy’s resources are fully employed.
Y
“Full employment” means that unemployment equals its natural
rate.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 14
Aggregate Supply in the Long RunAggregate Supply in the Long Run
Recall from chapter 3: In the long run, output is determined by factor supplies and technology
Full-employment output does not depend on the price level,
so the long run aggregate supply (LRAS) curve is vertical:
, ( )Y F K L
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 15
The long-run aggregate supply curveThe long-run aggregate supply curve
Y
P LRAS
Y
The LRAS curve is vertical at the full-employment level of output.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 16
Long-run effects of an increase in Long-run effects of an increase in MM
Y
P
AD1
AD2
LRAS
Y
An increase in M shifts the AD curve to the right.
P1
P2In the long run, this increases the price level…
…but leaves output the same.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 17
Aggregate Supply in the Short RunAggregate Supply in the Short Run
In the real world, many prices are sticky in the short run.
From now on we assume that all prices are stuck at a predetermined level in the short run…
…and that firms are willing to sell as much as their customers are willing to buy at that price level.
Therefore, the short-run aggregate supply (SRAS) curve is horizontal:
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 18
The short run aggregate supply curveThe short run aggregate supply curve
Y
P
PSRAS
The SRAS curve is horizontal:
The price level is fixed at a predetermined level, and firms sell as much as buyers demand.
Consider example of catalogue company: publishes price, and takes orders for quantity
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 19
Short-run effects of an increase in Short-run effects of an increase in MM
Y
P
AD1
AD2
…an increase in aggregate demand…
In the short run when prices are sticky,…
…causes output to rise.
PSRAS
Y2Y1
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 20
From the short run to the long runFrom the short run to the long run
Over time, prices gradually become “unstuck.” When they do, will they rise or fall?
Y Y
Y Y
Y Y
?
?
?
In the short-run equilibrium, if
then over time, the price level
will
This adjustment of prices is what moves the This adjustment of prices is what moves the economy to its long-run equilibrium.economy to its long-run equilibrium.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 21
The SR & LR effects increase in The SR & LR effects increase in MM
Y
P
AD1
AD2
LRAS
Y
PSRAS
P2
Y2
A = initial equilibrium
AB
CB = new short-
run equilib. after increase M
C = long-run equilibrium
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 22
Introducing shocks into frameworkIntroducing shocks into framework
shocks: exogenous changes in aggregate supply or demand
Shocks temporarily push the economy away from full-employment.
An example of a demand shock:exogenous decrease in velocity
If the money supply is held constant, then a decrease in V means people will be using their money in fewer transactions, causing a decrease in demand for goods and services:
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 23
LRAS
AD2
PSRAS
The effects of a negative demand shockThe effects of a negative demand shock
Y
P
AD1
Y
P2
Y2
The shock shifts AD left, causing output and employment to fall in the short run
AB
COver time, prices fall and the economy moves down its demand curve toward full-employment.
CHAPTER 9CHAPTER 9 Introduction to Economic Fluctuations Introduction to Economic Fluctuations slide 24
Supply shocksSupply shocks
A supply shock alters production costs, affects the prices that firms charge. (also called price shocks)
Examples of adverse supply shocks: Bad weather reduces crop yields, pushing up