1. Keynesian Income Determination
LECTURE 2
Keynesian Income Determination

2. Aggregate Expenditure
Defined as the total amount that firms and households plan to spend on goods and services at each level of income.
It can also be seen that the aggregate expenditure is the sum of expenditures on consumption, investment, government expenses and net exports.

3. Consumption Government
Spending
GDP = C + I + G + NX
Investment Net Exports

4. Income, Savings and their Determinants
A household can do 2 things with income:
(a) consume – buy goods and services.
(b) save.
Saving is the part of its income that a household does not consume in a given period.

5. Consumption
The consumption function shows the relationship between total consumer expenditures and total disposable income in the economy, holding all other determinants of consumer spending constant.

6. Marginal Propensities and the Multiplier
The slope of the consumption function is known as the marginal propensity to consume (MPC).
The MPC tells us how much more consumers will spend if disposable income rises by RM1.
MPC = Change in Disposable Income
Change in Consumption

8. Consumption Function

9. Example
Calculate the MPC for the graph below. What does the value imply?

10. Factors that Shift the Consumption Function
Any change in disposable income will cause a movement along the same consumption function, where else a change in other determinants will shift the consumption function.
Wealth
Price level
Real interest rate
Future income expectation

11. Wealth A source of purchasing power in addition to income.
Eg. A wealthy retiree with a huge bank balance may earn little current income when interest rates are low. But a high-flying investment banker who spends every penny of high income she earns will not accumulate much wealth.

12. Price Level
People hold a great deal of wealth in forms that are fixed in money terms. Bank accounts are the most obvious example, but government and corporate bonds also have fixed values in money terms.
The purchasing power of such money-fixed assets obviously declines whenever the price level rises, which means that the asset can buy less.
Eg. If the price level rises by 10%, a RM1,000 government bond will buy 10% less than it could when prices were lower.

13. Future Income Expectation
Real Interest Rate
A higher real rate of interest raises the rewards for saving and vice versa.
Future Income Expectation
When consumers expect income to increase in the future, current consumption will also increase and vice versa.

14. Equilibrium GDP Determination
Equilibrium GDP is that output level at which the total amount of goods and services produced, GDP, is just equal to the total amount of goods purchased.

15. Expenditure Schedule Real Expenditure (RM billions) C + I + G 6,100
6,000
4,800
3,900
, Real GDP (RM billions)
C + I + G + NX
C + I C

16. 6,000 E Output exceeds spending
The 45o line shows all the points at which output and spending are equal.
Real Expenditure (RM billions)
45o
C + I + G + NX
6, E Output exceeds spending
Equilibrium
Spending exceeds output
, Real GDP (RM billions)

17. Multiplier = Change in GDP
The Multiplier
The multiplier is the ratio of the change in equilibrium GDP divided by the original change in spending that causes the change in GDP.
Multiplier = Change in GDP
Change in Spending

18. The remarkable thing about the multiplier is that it shows that a change in spending will bring about an even larger change in equilibrium GDP on the demand side.

19. Eg. The expenditure schedule (values are in RM billion)
GDP
Consumption
Investment
Government
Spending
Net Exports
Total Expenditure
4,800
3,000
900
1,300
-100
5,100
5,200
3,300
5,400
5,600
3,600
5,700
6,000
3,900
6,400
4,200
6,300
6,800
4,500
6,600
7,200
6,900

20. Total expenditure after a RM200 billion increase in investment spending
GDP
Consumption
Investment
Government
Spending
Net Exports
Total Expenditure
4,800
3,000
1,100
1,300
-100
5,300
5,200
3,300
5,600
3,600
5,900
6,000
3,900
6,200
6,400
4,200
6,500
6,800
4,500
7,200
7,100

21. Referring the tables above, assume that firms now want to invest RM200 billion more than previously – for a total of RM1,100 billion.
The multiplier principle says that GDP will rise by more than the RM200 billion increase in investment.

22. Multiplier = Change in GDP
Change in Spending (I)
= RM800 billion
RM200 billion
= 4
Implication: Each additional RM1 of investment demand will add RM4 to equilibrium GDP.

23. Illustration of the Multiplier
Real Expenditure (RM billions)
45o
C + I + G + NX
C + I + G + NX
RM 200 billion
,000
6,800
Real GDP (RM billions)