1. Fun!!! With the MPC, MPS, and Multipliers
AP Macroeconomics
Fun!!! With the MPC, MPS, and Multipliers

2. Disposable Income = DI
Net Income
Paycheck
After-tax income

3. Marginal Propensity to Consume (MPC)
The fraction of any change in disposable income that is consumed. New $ = new C
MPC= Change in Consumption
Change in Disposable Income
MPC = ΔC/ΔDI

4. Marginal Propensity to Save (MPS)
The fraction of any change in disposable income that is saved.
New $ = new savings
MPS= Change in Savings
Change in Disposable Income
MPS = ΔS/ΔDI

5. Marginal Propensities
MPC + MPS = 1 {i.e. every new $ is either spent (C) or saved.}
.: MPC = 1 – MPS
.: MPS = 1 – MPC
Remember, people do two things with their disposable income, consume it or save it!

6. The Spending Multiplier Effect
Why does this happen?
Expenditures and income flow continuously which sets off a spending increase in the economy. New $ hits the circular flow….spending/earning/spending/earning….

7. The Spending Multiplier Effect
Ex. If the government increases defense spending by $1 Billion, then defense contractors will hire and pay more workers, which will increase aggregate spending by more than the original $1 Billion.

8. Calculating the Spending Multiplier
The Spending Multiplier can be calculated from the MPC or the MPS.
Multiplier = 1/1-MPC or 1/MPS
Multipliers are (+) when there is an increase in spending and (–) when there is a decrease

9. EXAMPLE CALCULATIONS
Business report states that in 2009, consumers spent only 80cents of each $, .: 1/1-mpc (1/1-.80) or 1/mps (1/.20) = ?
Now calculate spending multiplier for mpc or .90; .75; .60; .50

10. Marginal Analysis: What happens when a new unit is added?
MPC = What % of new DI will people ___________.
MPS = What % of new DI will people ___________.
MPC + MPS will always = ______.
The Spending Multiplier Effect
Assume new marginal income is created. Example: tax cut.
Assume that the tax cut averages a new $1000 of disposable income.
Assume that the current MPC will be 90% and the MPS will be 10%.
Notice: For each person getting a new $1000, several consumption events
can occur from that single amount of money. How long will the pattern continue? Economists use the Spending Multiplier Formula to estimate the number of times the pattern will repeat before the amount shrinks to a point where new spending stops. The formula is: 1/1-MPC, or 1/MPS.
Therefore, if the MPC is .9, how many new dollars of consumption will be created if society receives $1 million dollars? ________.
How many new dollars of consumption will be created if the MPC is only .5? ___________.
Person
MPC
MPS
First to get the new $
Second to use that $
Third to use that $
Fourth to use that $
Fifth to use that $
Total So Far of the Original $1000

11. Calculating the Tax Multiplier
When the government taxes, the multiplier works in reverse
Why?
Because now money is leaving the circular flow
Tax Multiplier (note: it’s negative)
= -MPC/1-MPC or -MPC/MPS
If there is a tax-CUT, then the multiplier is +, because there is now more money in the circular flow

12. Tax multiplier calculations
-mpc/1-mpc or –mpc/mps OR………
Assume a tax hike of .90 to equal
-.90/10……..answer?
Now calculate other tax multipliers with mpc of .80; .75; .60; .50

13. MPS, MPC, & Multipliers
Ex. Assume U.S. citizens spend 90¢ for every extra $1 they earn. Further assume that the real interest rate (r%) decreases, causing a $50 billion increase in gross private investment. Calculate the effect of a $50 billion increase in IG on U.S. Aggregate Demand (AD) or AE.
Step 1: Calculate the MPC and MPS
MPC = ΔC/ΔDI = .9/1 = .9
MPS = 1 – MPC = .10
Step 2: Determine which multiplier to use, and whether it’s + or -
The problem mentions an increase in Δ IG .: use a (+) spending multiplier
Step 3: Calculate the Spending and/or Tax Multiplier
1/MPS = 1/.10 = 10
Step 4: Calculate the Change in AD/AE
(Δ C, IG, G, or XN) * Spending Multiplier
($50 billion Δ IG) * (10) = $500 billion ΔAD/AE

14. MPS, MPC, & Multipliers
Ex. Assume Germany raises taxes on its citizens by €200 billion . Furthermore, assume that Germans save 25% of the change in their disposable income. Calculate the effect the €200 billion change in taxes on the German economy.
Step 1: Calculate the MPC and MPS
MPS = 25%(given in the problem) = .25
MPC = 1 – MPS = = .75
Step 2: Determine which multiplier to use, and whether it’s + or -
The problem mentions an increase in T .: use (-) tax multiplier
Step 3: Calculate the Spending and/or Tax Multiplier
-MPC/MPS = -.75/.25 = -3
Step 4: Calculate the Change in AD
(Δ Tax) * Tax Multiplier
(€200 billion Δ T) * (-3) = -€600 billion Δ in AD/AE

15. MPS, MPC, & Multipliers
Ex. Assume the Japanese spend 4/5 of their disposable income. Furthermore, assume that the Japanese government increases its spending by ¥50 trillion and in order to maintain a balanced budget simultaneously increases taxes by ¥50 trillion. Calculate the effect the ¥50 trillion change in government spending and ¥50 trillion change in taxes on Japanese Aggregate Demand or AE.
Step 1: Calculate the MPC and MPS
MPC = 4/5 (given in the problem) = .80
MPS = 1 – MPC = = .20
Step 2: Determine which multiplier to use, and whether it’s + or -
The problem mentions an increase in G and an increase in T .: combine a (+) spending with a (–) tax multiplier
Step 3: Calculate the Spending and Tax Multipliers
Spending Multiplier = 1/MPS = 1/.20 = 5
Tax Multiplier = -MPC/MPS = -.80/.20 = -4
Step 4: Calculate the Change in AD
[ Δ G * Spending Multiplier] + [ Δ T * Tax Multiplier]
[(¥50 trillion Δ G) * 5] + [(¥50 trillion Δ T) * -4]
[ ¥250 trillion ] + [ ¥200 trillion ] = ¥50 trillion Δ AD/AE

16. Assume the Japanese spend 4/5 of their disposable income
Assume the Japanese spend 4/5 of their disposable income. Furthermore, assume that the Japanese government increases its spending by ¥50 trillion and in order to maintain a balanced budget simultaneously increases taxes by ¥50 trillion. Calculate the effect the ¥50 trillion change in government spending and ¥50 trillion change in taxes on Japanese Aggregate Demand or AE.

17. The Balanced Budget Multiplier
That last problem was a pain, wasn’t it?
Remember when Government Spending increases are matched with an equal size increase in taxes, that the change ends up being = to the change in Government spending
Why?
1/MPS + -MPC/MPS = 1- MPC/MPS = MPS/MPS = 1
The balanced budget multiplier always = 1

18. Does a change in G have the same effect on GDP as a change in T?
No – G has a greater effect!
A change in G affects GDP directly by a multiple of the change in G.
A change in T affects GDP by a multiple of less than the change in T.
A change in T results in a change in Yd. Yd can be either spent (C) or saved (S); therefore, a change in T only affects GDP by a multiple of the change in C. The initial change in C is less than the change in T.

19. Effect of the the increase in G:
Determine the effect on GDP of an increase in G of $20 billion and the effect of a decrease in T of $20 billion. Assume the MPC = .80
Effect of the the increase in G:
Effect of the decrease in T:
1/1-.80 5
Multiplier = _________ = _____ 20 5
100 increase
_____ X ______ = ______ 20 16 4
 T of $20 billion   Yd _____   _____ C _____ S 16 5
80 increase which is less than
The increase of 100 from G.
_____ X ______ = ______

20. What would be the effect of an increase in taxes of $100 billion?
What would be the effect on the economy (GDP) of a decrease of $100 billion in G. Assume the MPS =.25
100 X 4 = $400 billion decrease in GDP
What would be the effect of an increase in taxes of $100 billion?
Increase T of $100 billion decreases income (Yd) by
100 billion. That means consumers will decrease spending
by $75 billion (.75 x100) and decrease saving by $25 bill.
The $75 billion decrease in C X the multiplier of 4 = a $300
Billion decrease in GDP.

21. Effect on GDP (economy)? Increase by $50 billion
Determine the effect on GDP of equal increases (balanced budget) in both G and T of $50 billion. Assume an MPC of .80.
Effect on Budget?
Effect on GDP (economy)? Increase by $50 billion
Multiplier = _____  C = _____
balanced
$40 billion
(.80x50) 5
Effect of G: 5 x 50 = 250 billion increase in GDP
Effect of T: decrease income by $50 billion; therefore,
C decreases by $40 billion and S decreases by $10 billion.
Therefore, $40 billion X 5 = 200 billion decrease in GDP
Net effect: 250 – 200 = $50 billion increase in GDP

22. Key Idea: The balanced budget multiplier is 1 x G
An increase in G and T of $50 billion would increase GDP by how much? ________
A decrease in G and T of $30 billion would decrease GDP by how much? _______
Conclusion: A balanced budget increase in G and T (spending and taxes are equal) has an ____________ effect on the economy.
A balanced budget decrease in spending and taxes has an ______________ effect on the budget.
50 billion
$30 billion
expansionary
contractionary

23. Multiplier Table Govt…..Invstmnt Spndng… Tax
MPC… .Multiplier…. Multiplier…. Multiplier
–9.0
–4.0
–3.0
–1.5
–1.0

24. Key Formula:  AE x M =  GDP
M = 1/MPS or 1/1-MPC or GDP/ AE
If the GDP gap is $100 billion, how much must AE (C, I, G, or Xn) increase to return the economy to YF if the MPC = .80? 5
M = 1/1-MPC = 1/ = 1/.20 = _____
 AE x M =  GDP 20 5
______ X ______ = Billion

25. Key Formula:  AE x M =  GDP
M = 1/MPS or 1/1-MPC or GDP/ AE
If the GDP gap is $40 billion and the MPS = .25, what amount must AE increase to close the GDP gap? 4
M = 1/MPS = 1/.25 = _____
 AE x M =  GDP
______ X ______ = 40 Billion 10 4

26. Key Formula:  AE x M =  GDP
M = 1/MPS or 1/1-MPC or GDP/ AE
If the economy is in a recession and has a GDP gap of $50 billion, how much must government increase G to close the GDP gap and return to full employment, assuming an MPS of .20? 5
M = 1/MPS = 1/.20 = _____
 AE x M =  GDP
______ X ______ = 50 Billion 10 5

27. If $500 billion in AE  $1000 billion in GDP, then how much would G have to  to reach a YF of $2000 billion?
$2000B
$1000B
$500B
$200B
$100B
Explanation:
1000/500 = 2 = Multiplier = GDP/AE
AE x Multiplier = GDP
G x 2 = 2000
G = 1000

28. The value of the spending multiplier decreases when?
Tax rates are decreased
Exports decrease
Imports decrease
Government expenditures decrease
The MPS increases
The multiplier = 1/MPS
1/.20 = 5
1/.40 = 2.5
As MPS increases, the
multiplier decreases.

29. Which of the following best explains why equilibrium income will rise by more than $100 in response to a $100 increase in G?
Incomes will    taxes
Incomes will   C
AE  PL
D. AE  MS   I
E. budget deficit  AE
Multiplier effect –
Spending becomes
Income which is either
Spent or saved; the
New expenditure gives
rise to more income,
which leads to more
spending.. . .

30. In a closed economy with no taxes in which the MPC is 0
In a closed economy with no taxes in which the MPC is 0.75, which of the following is true?
APC = fraction of income spent = .75 = 3/4ths
If income is $100, then saving is $75
If income is $100, then C is $50
If income is $200, then saving is $50
If income is 200, then C is $75
If income is $500, then S is $100
200 x .75 = $150 in consumption, leaving $50 in saving.

31. Suppose that Yd is $1000, C is $700, and the MPC is 0. 60
Suppose that Yd is $1000, C is $700, and the MPC is If Yd increases by $100, C and S will equal which of the following?
C _ S
YD = 1000
C = 700
S = 300 as a starting point
Yd = 100 and MPC = .60
C = .60 (100) = 60 and
 S = .40 (100) = 40
= 760 C
= 340 S

32. If at YF, government wants to increase its spending by $100 billion without inflation in the short run, it must do which of the following?
 T by greater than $100 B
 T by $100B
 T by less than $100 B
 T by $100 B
 by less than $100 B
G has a greater effect
on GDP than T; there-
fore the  T must be
Greater than the  G to
offset the increased G
and prevent further
Inflation.

33. If AE  from 200 to 300 solely due to a change in G leads to a change in GDP of 1000 to 1500, which of the following is true?
G = 100
GDP = 500
M = 5
G is 300 and the multiplier is 5
G is 100 and the multiplier is 5
G is 100 and C increases by 500
G and GDP increase by 500 each
C and GDP increase by 500 each

34. AP M/C QUESTION
An increase in the marginal propensity to consume causes an increase
in which of the following?
a. Marginal propensity to save
b. Spending multiplier
c. Saving rate
d. Exports
e. Aggregate supply

35. AC/DC MACROECONOMICS http://www.youtube.com/watch?v=Xg-0z5RWbAU