1. AE = [W + Ye – PL – r – mpc ∙ T + I + G + X ] + { mpc – mpm }Y
AD-AS-FE Model
AE equilibrium
At full employment, real GDP equals potential GDP and the unemployment rate equals the natural unemployment.
Y = YFE uc = g ≈ 3% p ≈ 2% u ≈ 5%
Potential GDP and the natural unemployment rate are determined by real factors and are independent of the PL.
Changes in the quantity of money change nominal GDP and the PL but have no effect on potential GDP.
Aggregate Demand (AD) is derived from Snarrian aggregate expenditure by imposing the AE equilibrium (Y = AE ) and then solving for PL.
AE = [W + Ye – PL – r – mpc ∙ T + I + G + X ] + { mpc – mpm }Y
AD is the relationship between the quantity of real GDP demanded and the price level when all other influences on expenditure plans remain the same
AD and Aggregate Supply (AS) determine equilibrium real GDP and the PL

2. Marginal propensity to save Marginal propensity to save
Aggregate Demand
“Snarrian” Aggregate Demand is found by substituting
AE = [W + Ye – PL – r – mpc ∙ T + I + G + X ] + { mpc – mpm }Y
Y = [W + Ye – PL – r – mpc ∙ T + I + G + X ] + { mpc – mpm }Y
PL = [W + Ye – r – mpc ∙ T + I + G + X ] + { mpc – mpm }Y – 1 Y
PL = [W + Ye – r – mpc ∙ T + I + G + X ] + { mpc – mpm – 1 }Y
PL = [W + Ye – r – mpc ∙ T + I + G + X ] – {– mpc + mpm + 1 }Y
PL = [W + Ye – r – mpc ∙ T + I + G + X ] – {1 – mpc + mpm }Y
PL = [W + Ye – r – mpc ∙ T + I + G + X ] – {mps + mpm }Y
Marginal propensity to save
Marginal propensity to save

3. PL = [W + Ye – r – mpc ∙ T + I + G + X ] – {mps + mpm }Y
Aggregate Demand
Snarrian Aggregate Demand
Example: In our continuing numerical example of the economy, W = 5, Ye = 7, PL = 8, r = 2, T = 3, I = 1, G = 3.5, X = 0.5 with mpc = 0.75, and mpm = Derive the AD equation.
First, ignore the fact that PL = 8 because AD is the relationship between real GDP and PL.
PL = [W + Ye – r – mpc ∙ T + I + G + X ] – {mps + mpm }Y
PL = [5 + 7 – 2 – 0.75 ∙ ] – { }∙ Y
PL = – 0.5 Y
When Y = 0
PL = – 0.5 (0) = 12.75
When Y = 9.5
PL = – 0.5 (9.5) = 8

4. Aggregate Demand Snarrian AD PL 12.75 8 AD 9.5 Y Example (continued ):
Point 1
Y = 0
PL = 12.75
Point 2
Y = 9.5
PL = 8
By assumption, aggregate planned expenditure equals real GDP (Y = AE ).
In the AE model, Y = 9.5 when PL = 8 at the equilibrium point. PL
12.75 8 AD
9.5 Y

5. Increased government spending increases AD.
Aggregate Demand
Snarrian AD
Example: What happens if government spending is increased to $4 trillion (G = 4)?
PL = [5 + 7 – 2 – 0.75 ∙ ] – { }∙ Y
PL = – 0.5 Y 4 PL
Increased government spending increases AD.
This increases real GDP provided the price level remains at $8 thousand.
PL = – 0.5 Y
13.25
8 = – 0.5 Y
12.75
0.5 Y= 5.25
Y= 10.5 8
AD’
Note: Increasing G raises the $500 billion budget deficit to $1 trillion AD
9.5
10.5 Y

6. Aggregate Demand 2.5 Snarrian Aggregate Demand
Example: What happens if taxes are lowered to $2.5 trillion (T = 2.5) instead?
PL = [5 + 7 – 2 – 0.75 ∙ ] – { }∙ Y
PL = – 0.5 Y
2.5 PL
PL = – 0.5 Y
13.125
The tax cut increases AD.
This increases real GDP provided the price level remains at $8 thousand.
8 = – 0.5 Y
12.75
0.5 Y= 5.125
Y= 10.25 8
AD’
Note: Cutting T raises the $500 billion budget deficit to $1 trillion AD
9.5
10.25 Y

7. Excel Simulation Assignment 4
Aggregate Demand
Aggregate Demand
PL = [W + Ye – r – mpc ∙ T + I + G + X ] – { mps + mpm }∙ Y
AD increases if W, Ye, I, G or X increase OR if r or T decrease
AD decreases if W, Ye, I, G or X decrease OR if r or T increase
The Congress and President are in charge of fiscal policy.
Expansionary fiscal policy involves a cut in T and/or increase in G
Restrictive fiscal policy involves a raising T and/or cutting G
The Federal Reserve (our central bank) is in charge of monetary policy
Expansionary monetary policy involves lowering the federal funds interest rate
Restrictive monetary policy involves raising the federal funds interest rate
Excel Simulation Assignment 4

8. Potential GDP Potential GDP is determined by the quantities of
Labor employed
Capital, human capital, and the state of technology
Land and natural resources
Entrepreneurial talent
At full employment (Y = YFE, g ≈ 3%, p ≈ 2%, uc = 0, u ≈ 5%),
The real wage rate makes the quantity of labor demanded equal to the quantity of labor supplied.
Along the potential GDP line, when the price level changes the money wage rate changes to keep the real wage rate at the full-employment level.
Since u equals the natural rate of unemployment there is no pressure on inflation to change
Over the business cycle
The quantity of labor employed fluctuates around its full employment level.
Real GDP fluctuates around potential GDP

9. Potential GDP Full-employment
Example: Suppose the economy’s production function shows the volume of output that can be produced by its labor force of size L given levels of K units of capital, R units of resources and z percent of the knowledge/talent that is contained in the universe.
Suppose there are a total of L = 144 (million) workers in the economy with resources, capital, and technology/talent currently at R = 400 (million acres of land and barrels of oil), K = 100 (million machines/roads/networks) and z = 1 (percent).
What is the economy’s short-run production function? Graph it.

10. Potential GDP Full-employment L Y 0.00 50 7.07 100 10.00 150 12.25
Example (continued):
Graph the economy’s short-run production function: L Y
0.00 50
7.07
100
10.00
150
12.25 er

11. Potential GDP Full-employment Example (continued):
Compute potential GDP.
YFE = 12 (trillion $) 12
144 er

12. Potential GDP Full-employment Example (continued):
Compute the output of the economy if only 121 million of the 144 million in the labor force are working.
Y = 11 (trillion $) 11
23 million workers are (cyclically) unemployed, resulting in Y < YFE
121
144 er

13. Since Y > YFE the unemployment rate is ‘low’
Potential GDP
Full-employment
Example (continued):
Compute the output of the economy if all 144 million workers in the labor force are full time (40 hours per week) and 50 million of them are working 20 hours of overtime per week.
Since 50 million are working an extra 20 hours/wk, the effective size of the (fulltime) work force is
L = /2 = 169 13
Since Y > YFE the unemployment rate is ‘low’
144 er

14. Potential GDP Full-employment Example (continued):
Compute potential GDP if capital increases to K = 121 (million machines/roads/networks). What is the new level of potential GDP?
121
13.2
YFE = 13.2 (trillion $)
144 er

15. Together, AS and AD determine equilibrium real GDP and the PL
Potential GDP
Full-employment
Example (continued):
Increases in an economy’s resources and knowledge/talent have the same effect as an increase in capital.
Graph the potential GDP you computed in part (3) with AD below. PL
YFE
Together, AS and AD determine equilibrium real GDP and the PL
The goal of policy makers is to keep equilibrium real GDP “close” to potential GDP with
g ≈ 3%
p ≈ 2%
u ≈ 5%
12.75 AD 12 Y

16. PL = [w + p + t – z – K – R – L ] + b ∙ YAS
Aggregate Supply
Aggregate Supply is the relationship between the quantity of real GDP supplied and PL
when all other influences on production plans remain the same
The AS curve is positively sloped (AS slope = b )
Firms maximize profits. If prices increase while all other costs are constant, production rises because it is more profitable. Firm supply, industry supply and AS slope up.
Alternatively, when PL rises with constant wages, real wages falls, employment rises, and quantity of real GDP supplied rises.
Shifters of AS are contained in its intercept:
The money wage rate changes (w).
The money prices of other resources change (p).
Government changes supply-side taxes (t )
Potential GDP changes:
Advances in technology (z)
Increases in the size of the Labor Force (L)
Increased public or private investment in capital (K)
Increased Land and natural resources (R)
The general form of AS:
PL = [w + p + t – z – K – R – L ] + b ∙ YAS
Along the AS curve, the only influence on production plans that changes is PL. That is, the quantity of real GDP supplied increases (decreases) when the PL rises (falls).

17. PL = [w + p + t – z – K – R – L ] + b ∙ YAS
Aggregate Supply
Snarrian Aggregate Supply
Example: Suppose money wage rate is $400 per week (w = 400) and money prices of other resources of $230 per week (p = 230) given a supply-side tax rate of percent (t = 15.75), technological advancement of 1 percent (z = 1), accumulated capital of 100 million machines/roads/networks (K = 100), 400 million acres of land and barrels of oil (R = 400), and a labor force of 144 million workers (L = 144).
Derive the AS equation which has a slope of b = 0.5.
PL = [w + p + t – z – K – R – L ] + b ∙ YAS
PL = [ – 1 – 100 – 400 – 144] YAS
PL = Y
When Y = 0
PL = (0) = 0.75
When Y = 12
PL = (12) = 6.75

18. Aggregate Supply Snarrian AS Example (continued ) Graph AS Point 1
6.75
0.75 12 Y

19. Supply-side tax cuts increase AS.
Aggregate Supply
Snarrian AS
Example (continued )
What happens if government cuts supply-side taxes to 15 percent (t = 15)?
PL = [ – 1 – 100 – 400 – 144] YAS
PL = 0.5 Y 15 PL
Supply-side tax cuts increase AS.
This increases real GDP provided the price level remains at 6.75 (thousand $). AS
AS’
6.75
PL = 0.5 Y
6.75 = 0.5 Y
Y= 13.5
0.75 12 Y
13.5

20. Aggregate Supply Snarrian AS Example (continued):
Graph potential GDP (YFE = 12) with AS equation found in part (1).
PL = Y PL
YFE
If real GDP equals YFE, the PL = 6.75
If the PL is greater than 6.75, real GDP exceeds potential GDP.
If the PL < 6.75, real GDP is less than potential GDP AS
6.75
0.75 Y 12

21. Aggregate Supply Snarrian AS Example (continued):
Show what happens to AS and YFE when technology increases.
PL = [w + p + t – z – K – R – L ] + b ∙ YAS PL
YFE
13.5
YFE
Potential GDP immediately shifts to the right
The increases in z decrease the value of the AS intercept.
AS increases (shifts to the right) AS AS
6.75 Y 12

22. Together, AS and AD determine equilibrium real GDP and the PL
Aggregate Supply
Snarrian AS
Example (continued):
Graph AS with potential GDP and AD below.
PL = Y
PL = (12) = 6.75
Together, AS and AD determine equilibrium real GDP and the PL
The goal of policy makers is to keep equilibrium real GDP “close” to potential GDP with
g ≈ 3%
p ≈ 2%
u ≈ 5% PL
YFE AS
0.75
6.75 AD Y 12

23. PL = [w + p + t – z – K – R – L ] + b ∙ YAS
Aggregate Supply
Aggregate Supply
PL = [w + p + t – z – K – R – L ] + b ∙ YAS
AS decreases if w, p, or t increase OR if z, K, R or L decrease
AS increases if w, p, or t decrease OR if z, K , R or L increase
The Congress and President are in charge of fiscal policy.
Expansionary supply-side fiscal policy involves cutting t
Restrictive supply-side fiscal policy involves raising t
The Federal Reserve (our central bank) is in charge of monetary policy
Expansionary monetary policy lowers the federal funds interest rate
Restrictive monetary policy raises the federal funds interest rate

24. AD-AS-YFE Equilibrium
Inflationary gaps
Example: Suppose potential GDP is $11 trillion and AS and AD are given by
PL = – YAS PL = – 0.5 Y AD
Graph AD, AS and YFE. PL
YFE AD
15.25 AS
-0.25
AD graph
PL = – 0.5(11) = 9.75
9.75
AS graph
PL = – (11) = 8 8 Y 11

25. AD-AS-YFE Equilibrium
Inflationary gaps
Example:
Compute equilibrium real GDP and PL. PL
YFE
Real GDP
– Y = – 0.5Y
0.75Y = 15.5 – 0.5Y
1.25Y = 15.5
Y = 12.4
PL and check
PL = – (12.4) = 9.05
PL = – 0.5(12.4) = 9.05 AD
15.25 AS
-0.25
9.75
9.05 8 Y 11
12.4

26. AD-AS-YFE Equilibrium
Inflationary gaps
Example:
Is the economy in a recessionary or inflationary gap?
PL = [w + p + t – z – K – R – L ] + b∙Y
AS’
Since real GDP exceeds potential GDP, the economy is in an inflationary gap.
Workers work overtime and/or more than one job, and firms compete for scarce labor.
The unemployment is say
u = 4%, which is lower than the natural rate of 5%.
For these reasons, there are upward pressures on wages. This raises AS until the gap is closed. PL
YFE AD
15.25 AS
-0.25
9.75
9.05 Y 11
12.4

27. AD-AS-YFE Equilibrium
Inflationary gaps
Example:
Is the economy in a recessionary or inflationary gap?
AS’
Allowing gaps to close on their own via changes in wages is a laissez faire policy.
Today, inflationary gaps tend to close faster.
The inflation redistributes income from those on fixed incomes (pensioners) to those with variable income (wages adjusted for inflation)
Governments have also used inflation as a tax to avoid cutting G or increasing T. PL
YFE AD
15.25
9.75 Y 11

28. AD-AS-YFE Equilibrium
Recessionary gap
Example: Suppose potential GDP is $13 trillion and AS and AD are given by
PL = – YAS PL = – 0.5 Y AD
Graph AD, AS and YFE. PL
YFE
AS graph
PL = – (13) = 9.5 AD
15.25 AS
-0.25
9.5
AD graph
PL = – 0.5(13) = 8.75
8.75 Y 13

29. AD-AS-YFE Equilibrium
Recessionary gap
Example:
Compute equilibrium real GDP and PL. PL
YFE
Real GDP
– Y = – 0.5Y
0.75Y = 15.5 – 0.5Y
1.25Y = 15.5
Y = 12.4
PL and check
PL = – (12.4) = 9.05
PL = – 0.5(12.4) = 9.05 AD
15.25 AS
-0.25
9.5
9.05
8.75 Y
12.4 13

30. AD-AS-YFE Equilibrium
Recessionary gap
Example:
Is the economy in a recessionary or inflationary gap?
PL = [w + p + t – z – K – R – L ] + b∙Y
Since real GDP is less than potential GDP, the economy is in a recessionary gap.
Factories, resources, and workers are not being fully utilized.
The unemployment is say
u = 8.5%, which is higher than the natural rate of 5%.
The surplus of workers bids down wages, which lowers AS until the gap is closed. PL
YFE AD
15.25 AS
-0.25
AS’
9.05
8.75 Y
12.4 13

31. AD-AS-YFE Equilibrium
Recessionary gap
Example:
Is the economy in a recessionary or inflationary gap?
If the government does nothing (laissez faire) when unemployment is high, prices in general fall (negative relationship).
Today, recessionary gaps close relatively slower than inflationary gaps.
The federal minimum wage was enacted in 1938.
John L. Lewis (UMW, CIO, USWA) organized millions of workers in the 1930s. PL
YFE AD
15.25
AS’
8.75 Y 13

32. AD-AS-YFE Equilibrium
Recessionary gap
Example:
Is the economy in a recessionary or inflationary gap?
Deflation sounds good because lower prices raise purchasing power.
However, deflation causes hardships for those whose net worth is mostly held in illiquid assets (homes).
Deflation amplifies debt since it was incurred when wages were higher. The same payment with a lower wage reduces purchasing power.
Deflation amplifies a loan's interest rate. PL
YFE AD
15.25
AS’
8.75 Y 13

33. AD-AS-YFE Equilibrium
Induced inflationary gaps
Example: Suppose potential GDP is $12.4 trillion and AS and AD are given by
PL = – YAS PL = – 0.5 Y AD
Graph AD, AS and YFE. PL
YFE AD
15.25 AS
-0.25
AD graph
PL = – 0.5(12.4) = 9.05
9.05
AS graph
PL = – (12.4) = 9.05 Y
12.4

34. AD-AS-YFE Equilibrium
Induced inflationary gaps
Example:
Show what happens if policy makers cut T or increase G.
PL = [W + Ye – r – mpc ∙ T + I + G + X ] – {mps + mpm }Y
Increasing G and cutting T when the economy is at full-employment induces an inflationary gap.
The policy boosts real GDP but at a cost (higher prices)
If nothing is done to combat this stimulus, wages will rise as labor markets tighten. This shifts AS up.
Hence, the increase in GDP was only temporary.
Prices soar even more.
PL = [w + p + t – z – K – R – L ] + b∙Y PL
YFE
AS’ AS
AD’ AD Y