1. Chapter # 3 Keynesian Theory of Income and Employment

2. Chapter`s outlines Introduction to Keynes` Theory
Determination of NI in two sector economy.
Two methods for determination of National Income.
AD & AS method.
Saving & Investment Method.
Determination of NI in three sector economy. numerical examples.

3. Introduction to Keynes theory
In the year 1936 Lord John Maynard Keynes’ General Theory of Employment, Income and Rate of Interest was first published..
His followers Harrod, Domar, Kaldor, Solow etc. have ever since widened the scope of macroeconomic analysis.

4. Introduction…….. Cont`d
Keynes has introduced a variety of new tools of analysis.
His equations of income and expenditure, consumption function, law of marginal propensity to consume (MPC), Multiplier operations, Investment Function and Marginal Efficiency Of Capital (MEC), identity between Savings and Investment, and monetary Liquidity Preference Theory of interest accompanied by speculative motive for demand for money are some of his important contributions.

5. Introduction…….. Cont`d
Keynes denied the classical belief that the free enterprise system is a self regulating one and asserted that such a system requires periodic intervention of the public authority to avoid fluctuations and instability in economic activities.
Besides, Keynes was building an entirely new structure of economic analysis to study and redress the problem of unemployment..

6. Determination of Equilibrium level of NI in TWO Sector Economy

7. Assumptions Two sector economy i.e. consumer and producers Y= C+I
The consumption expenditures (C) has the following equation C= Co + cY
The investment expenditure (I) consist of autonomous investment
The saving equation is as S= -So + sY
The output side of NI will be as Y= C + S

8. Two methods
AD and AS Method
Saving and Investment Method

9. 1 AD and AS Method Aggregate Demand (AD) Y = C + I
Total demand for goods and services produced in a year OR
Total National expenditure incurred on the final goods and services produced in a country.

10. Aggregate Supply (AS) Y = C+S
In a two sector economy, “AS” consist of total output produced in the economy . OR
“AS” is a national income which has been produced by the factor of production.

11. Determination of equilibrium Level of NI
C+S
C+ I < C+S Y B
C+I
C+ I= C+S E .
C+ I > C+S A x Y1 Y2 Y3
National income

12. Explanation of Graph
In this figure the equilibrium level of NI is determined at E where C+I=C+S, and OY2 is the equilibrium level of NI.
The equilibrium can not take place at point OY1 because here C+I > C+S. This would lead to increase in income. Similarly at OY3, C+I < C+S which would have the effect of reducing the income of the country.
Thus we find that it is OY2 level of income where aggregate demand is equal to aggregate supply.

13. Numerical explanation of NI determination in two sector Economy --- AD/AS Method
If C= Y and I=I0 =80
Then NI Y= C+I
Putting the value of C & I in equation
Y = Y + 80
Y- 0.6Y = 120
0.4Y =120 dividing both sides by 0.4
0.4Y/0.4 = 120/0.4
Thus Y = 300

14. Cont`d And we know that C= 40+0.6(Y)
Put the value of Y in equation, we get C = (300)
C =
C = 220
Now Y = 300, C= 220, so S ?
As Y=C+S so S= 80= I0
Hence at Y=300 , S=I so income is determined at level Y=300

15. 2 Saving & Investment Method
The part of income which is not consumed is called saving.
Saving depends upon income S= f(Y)
while S = -S0 + sY
-S0 shows –ve Y and sY shows induced saving.

16. Cont`d
The part of the income which is spent on the purpose other than consumption is called investment.
According to Keynes investment is autonomous i,e. I=I0

17. Cont`d . S=f(Y) Y I < S I=S I > S I=I0 A E B Y1 Y2 Y3 x
Saving & investment
I=I0 A E B Y1 Y2 Y3 x
National income

18. Explanation of graph
In this figure, the equilibrium level of NI is determined where I=S. Accordingly OY2 is the equilibrium level of NI. Equilibrium does not take place at OY1 because here I>S, this would result in increase in income.
Similarly at OY3, I<S which would result in decrease in NI.
So we find that OY2 is the equilibrium level of NI.

19. Numerical explanation of NI determination in two sector Economy --- AD/AS Method
If S= Y and I=I0 =80
Then NI S = I
Putting the value of C & I in equation
Y = 80
0.4Y = 120
0.4Y =120 dividing both sides by 0.4
0.4Y/0.4 = 120/0.4
Thus Y = 300 so S = (300)
S =
S = 80 =I

20. Example to be solved???
Suppose the consumption function is given by C= Y, while I0 =50
What is the equilibrium level of income?
What is the level of saving at equilibrium level?
If I0 (Autonomous Investment) increases to 100 what will be the new equilibrium level of NI.

21. Inflationary and Deflationary Gaps
Inflationary Gaps
The equilibrium level of NI may be at above full employment. This situation occurs when at the level of full employment AD is greater than AS.

22. Inflationary Gap cont`d
When level of investment in an economy exceeds the investment level required to full employment, the equilibrium level of NI will be above the full employment level. This gap between current investment and required investment level shows a inflationary gap.

23. Deflationary Gaps
The equilibrium level of NI may be at below full employment. This situation occurs when at the level of full employment AD is less than AS.

24. CONT`D
When level of investment in an economy is below the investment level required to full employment, the equilibrium level of NI will also be below the full employment level. This gap between current investment and required investment level shows a deflationary gap.

25. Determination of Equilibrium level of NI in THREE Sector Economy

26. Determination of equilibrium level of NI in three sector economy
Three sector economy means- consumer, producers and Government, Y= C+S+T & Y=C+I+G
The consumption expenditures (C) has the following equation C= Co + cYd whereas Yd= Y-T
The investment expenditure (I) consist of autonomous investment, I=I0

27. Determination of equilibrium level of NI in three sector economy cont`d
The saving equation is as S= -So + sYd
5 G =G0 , is autonomous government expenditure.
AD = Y = C+I+G &
AS = Y = C+S+T

28. Cont`d . C+S C+I+G Y B C+I E A x Y1 Y2 Y3 National income
Consumption, invest, Govt. A x Y1 Y2 Y3
National income

29. Numerical example If C= 40+0.6Yd , I=80, G=20, T=10 Then Y=C+I+G
Y= [Y-T]
Y= [Y -10]
Y= Y
Y -0.6 = 134
0.4Y =134
Y = 134/0.4
Y = 335

30. Cont`d Now Putting the value of Y in C Yd = Y-T Yd= 335-10= 325
C= Hence Y= C + I + G
335=
335=335

31. Example to be solved If C = 100+0.75Y, G0= 20, & I0= 50
Find the equilibrium level of National income?
Prove that S=I0+G0

32. Another Example…??? If C = 100+0.75Yd, (Yd =Y-T) T=20 G0= 20, & I0= 50
Find the equilibrium level of National income?
Prove that S+T=I0+G0

33. THANK YOU