1. Equilibrium in Aggregate Economy

2. Equilibrium in the Aggregate Economy
Changes in the SAS, AD, and LAS curves affect short-run and long-run equilibrium.

3. Short-Run Equilibrium
Short-run equilibrium is where the AS and AD curves intersect.

4. Short-Run Equilibrium
Increases (decreases) in aggregate demand lead to higher (lower) real output and higher (lower) price level.
Upward (downward) shift the SAS curve lead to lower (higher) real output and higher (lower) price level.

5. Short-Run Equilibrium
Short-run equilibrium is
where SAS = AD0 (point
E). Equilibrium output is
Y0 and the price level is
P0.
AD1 Y0 E P0
AD0
Price level Y1 P1 F
SAS
If AD increases to AD1,
equilibrium output
increases to Y1 and the
price level increases to P1. P0 E
AD0 Y0
Real output

6. Short-Run Equilibrium
Short-run equilibrium is
where SAS0 = AD (point
E). Equilibrium output is
Y0 and the price level is
P0.
Price level G
SAS1 Y1 P1 Y0 P0
SAS0 E
SAS0
If SAS increases to SAS1,
equilibrium output
decreases to Y1 and the
price level increases to P1
(point G). E P0 AD Y0
Real output

7. Long-Run Equilibrium
Long-run equilibrium is where the AD and long-run aggregate supply curves intersect.
In the long run, output is fixed and the price level is variable.

8. Long-Run Equilibrium Aggregate demand determines the price level.
Increases (decreases) in aggregate demand lead to higher (lower) prices.

9. Long-Run Equilibrium: Shift in Aggregate Demand
Real output
Price level
AD1
LAS
AD0 H P1 P0 Y0 E

10. Long-Run Equilibrium AD1 LAS Price level Long-run equilibrium is
point E where AD0 = LAS.
Equilibrium output is at
potential output YP and
the price level is Po. H P1
An increase in AD to AD1
increases the price level
to P1 but output is un-
changed at YP. E P0
AD0
In the long-run output is
fixed, and the price level
is variable. YP
Real output

11. Integrating the Short-Run and Long-Run Frameworks
The economy is in both short-run and long-run equilibrium when all three curves intersect in the same location.

12. Integrating the Short-Run and Long-Run Frameworks
The ideal situation is for aggregate demand to grow at the same rate as aggregate supply and potential output.
Unemployment and growth are at their target rates with no inflation.

13. Integrating Short-Run and Long-Run Equilibrium
The economy is in long-run and short-run equilibrium at point E where AD=SAS=LAS and output is YP and the price level is P0.
LAS
SAS E
Price level
AD grows at the same rate as potential output, so that unemployment and inflation are very low. P0 AD YP
Real output

14. Recessionary Gap
A recessionary gap is the amount by which equilibrium output is below potential output.
LAS
If the economy is at point A, some resources are unemployed and the recessionary gap is YP – Y1. Y1 P0 A
SAS0
SAS0 A P1 B P0
Price level
If resources are unemployed for a long time, eventually wages and prices decrease. SAS shifts down to SAS1 and the economy is in long-run and short-run equilibrium at B.
SAS1 AD
Recessionary
gap Y1 YP
Real output

15. The Recessionary Gap
If the economy remains at this level for a long time, there would be an excess supply of factors of production.
Costs and wages would tend to fall.

16. Inflationary Gap
LAS
An inflationary gap is the amount by which equilibrium output is above potential output.
Price level
If the economy is at point C, resources are being used beyond their potential and the inflationary gap is YP – Y2.
SAS2 D P2 Y2
SAS0 P0 C C
SAS0 P0 AD
If resources are used beyond their potential, eventually wages and prices increase. SAS shifts up to SAS2 and the economy is in long-run and short-run equilibrium at D at a higher price level, P2.
Inflationary
gap YP Y2
Real
output

17. The Inflationary Gap
The inflationary gap occurs when the economy is above potential that exists at the current price level.
Factor prices rise causing the SAS curve to shift up.
The price level rises, and the inflationary gap is eliminated.

18. The Economy Beyond Potential
When the economy operates below its potential, firms can hire additional factors of production without increasing production costs.
Once the economy reaches its potential output, that is no longer possible.

19. The Economy Beyond Potential
As firms compete for resources, costs rise beyond productivity increases.
The short-run AS curve shifts up and the price level rises.

20. The Economy Beyond Potential
The economy will slow down by itself or the government will step in with a policy to contract output and eliminate the inflationary gap.

21. Expansionary Fiscal Policy
Price level
If the economy is at equilibrium at point A, there is a recessionary gap Y0 – YP.
LAS
AD1 B
The appropriate fiscal policy is to increase government spending and/or decrease taxes. P1 YP
SAS P0 A A
AD increases to AD1 and output returns to potential output YP and prices increase slightly to P1.
AD0 Y0
Real output

22. Contractionary Fiscal Policy
LAS
If the economy is at equilibrium at point B, there is an inflationary gap Y2 – YP.
AD2
The appropriate fiscal policy is to decrease government spending and/or increase taxes. B AS P2
Price level
AD0
AD decreases to AD2 and output returns to potential output YP and inflation is prevented. YP Y2
Real output

23. Macro Policy Is More Complicated Than It Looks
Using the AS/AD model to analyze the economy is more complicated than it looks.
Implementing fiscal policy.
Estimating potential output.
Effectiveness of fiscal policy.

24. The Problem of Implementing Fiscal Policy
There is no guarantee that government will do what the economy needs to be done.
Implementing government spending and tax changes is a slow legislative process.
Government spending and tax decisions are made for political rather than for economic reasons.

25. The Problem of Estimating Potential Output
Increasing AD when the economy is operating at its potential will accelerate inflation by shifting up the SAS curve.

26. The Problem of Estimating Potential Output
One way of estimating potential output is to estimate the target rate of unemployment.
Target rate of unemployment – the rate below which inflation began to accelerate in the past.

27. The Problem of Estimating Potential Output
Unfortunately, the target rate of unemployment fluctuates and is difficult to predict.
For example, there is structural but no cyclical unemployment at potential output – it is difficult to differentiate between the two.

28. The Problem of Estimating Potential Output
Another way to determine potential output is to add the normal growth factor (3%) the economy’s previous level.
Estimating the economy’s potential from past growth rates is complicated.

29. The Questionable Effectiveness of Fiscal Policy
The effectiveness of fiscal policy depends on the government’s ability to perceive a problem and react appropriately to it.

30. The Questionable Effectiveness of Fiscal Policy
Countercyclical fiscal policy – fiscal policy in which the government offsets any change in aggregate expenditures that would create a business cycle.