2 determination of gdp in the short run
Download as PPT, PDF0 likes192 views
This document provides an overview of a basic macroeconomic model for determining GDP in the short-run. It explains that GDP is determined by aggregate expenditure, which includes consumption, investment, government spending, and net exports. Consumption depends on disposable income and wealth, while investment depends on interest rates and business confidence. Equilibrium GDP occurs when aggregate expenditure equals total output.
![What Determines Aggregate Expenditure
A change in personal disposable income leads to a
change in private consumption and saving.
The responsiveness of these changes is measured
by the marginal propensity to consume [MPC] and
the marginal propensity to save [MPS], which are
both positive and sum to one.
This indicates that, by definition, all disposable
income is either spent on consumption or saved.
A BASIC MODEL OF THE DETERMINATION OF GDP](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-5-320.jpg)
![ The simple multiplier is the multiplier
when the price level is constant.
It is equal to 1/[1 - z], where z is the
marginal propensity to spend out of
national income.
Thus the larger z is, the larger is the
multiplier. It is a basic prediction of
macroeconomics that the simple
multiplier, relating £1 worth of increased
spending on domestic output to the
resulting increase in GDP, is greater than
unity.
A BASIC MODEL OF THE DETERMINATION OF GDP](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-13-320.jpg)
![500 1000 1500
450
450
2000
500
1000
1500
2000
(i). Consumption Function [£ million]
Real Disposable Income
C S
500 1000 1500 2000
The Consumption and Saving Functions
-500
-100
0
250
500
Real Disposable Income
(ii). Saving Function [£ million]
Note: Initially, at zero income consumers are drawing down on existing
savings / assets .](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-17-320.jpg)
![1000 2000 3000 4000
1000
2000
3000
Real National Income Function [GDP] [£m]
350
An Aggregate Expenditure Function
4000
5000
AE
5000](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-22-320.jpg)
![0
1000 2000
1000
2000
3000
Real National Income [GDP] [£m]
350
[i]. An Aggregate Expenditure Function[AE = Y]
3000
450
450
[AE = Y]
S
I
[ii]. Saving Function[S = I]
Real National Income [GDP] [£m]
3000
2000
1000
500
-100
-500
0
Desired
saving
(£m)
250
Y0
Equilibrium GDP
Y0
E0](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-25-320.jpg)
![0
450
AE = Y
Real National Income [GDP]
The Simple Multiplier](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-28-320.jpg)
![Y0
0
E0
AE0
e0
450
AE = Y
Real National Income [GDP]
The Simple Multiplier](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-29-320.jpg)
![Y0
0
AE1
Y1
E0
E1
AE0
e1
e’1
e0
450
a
Y
A
AE = Y
Real National Income [GDP]
The Simple Multiplier](https://image.slidesharecdn.com/2determinationofgdpintheshortrun-210328121731/85/2-determination-of-gdp-in-the-short-run-30-320.jpg)
2 determination of gdp in the short run
- 1. A Basic Model of the Determination of GDP in the Short Term Chapter 16
- 2. Learning Outcomes The macroeconomic theory that we now study explains the deviation of actual from potential GDP, that is the GDP gap. The determination of GDP in the short run depends on the behaviour of key categories of aggregate spending: consumption, investment, government spending, and net exports.
- 3. Learning Outcomes Consumption spending depends on disposable income and wealth. Investment spending depends on real interest rates and business confidence. A necessary condition for GDP to be in equilibrium is that desired domestic spending equals actual output.
- 4. What Determines Aggregate Expenditure Desired aggregate expenditure includes desired consumption, desired investment, and desired government expenditures, plus desired net exports. It is the amount that economic agents want to spend on purchasing the national product. In this chapter we consider only consumption and investment. A BASIC MODEL OF THE DETERMINATION OF GDP
- 5. What Determines Aggregate Expenditure A change in personal disposable income leads to a change in private consumption and saving. The responsiveness of these changes is measured by the marginal propensity to consume [MPC] and the marginal propensity to save [MPS], which are both positive and sum to one. This indicates that, by definition, all disposable income is either spent on consumption or saved. A BASIC MODEL OF THE DETERMINATION OF GDP
- 6. A change in wealth tends to cause a change in the allocation of disposable income between consumption and saving. The change in consumption is positively related to the change in wealth, while the change in saving is negatively related to this change. Consumption is negatively related to change in interest rates. A BASIC MODEL OF THE DETERMINATION OF GDP
- 7. Investment consists of inventory accumulation, residential housing construction and business fixed capital formation. Investment depends, among other things, on real interest rates and business confidence. Higher the interest rates lower the level of desired inventory of goods and material, lower the spending for residential construction and lower the investment in fixed capital. Current profits which largely finance capital formation are an important determinant of investment In our simple theory investment is treated as autonomous, or exogenous, as is the constant term in the consumption function, called autonomous consumption. The part of consumption that responds to changes in income is called induced spending. A BASIC MODEL OF THE DETERMINATION OF GDP
- 8. Equilibrium GDP At the equilibrium level of GDP, purchasers wish to buy exactly the amount of national output that is being produced. At GDP above equilibrium, desired expenditure falls short of national output, and output will sooner or later be curtailed. A BASIC MODEL OF THE DETERMINATION OF GDP
- 9. Equilibrium GDP At GDP below equilibrium, desired expenditure exceeds national output, and output will sooner or later be increased. In a closed economy with no government, desired saving equals desired investment at equilibrium GDP. A BASIC MODEL OF THE DETERMINATION OF GDP
- 10. Equilibrium GDP is represented graphically by the point at which the aggregate expenditure curve cuts the 450 line, that is, where total desired expenditure equals total output. This is the same level of GDP at which the saving function intersects the investment function. A BASIC MODEL OF THE DETERMINATION OF GDP
- 11. Changes in GDP With a constant price level, equilibrium GDP is increased by a rise in the desired consumption or investment expenditure that is associated with each level of national income. Equilibrium GDP is decreased by a fall in desired spending. A BASIC MODEL OF THE DETERMINATION OF GDP
- 12. Changes in GDP The magnitude of the effect on GDP of shifts in autonomous expenditure is given by the multiplier. It is defined as K = Y/A, where A is the change in autonomous spending and Y the resulting increase in GDP. A BASIC MODEL OF THE DETERMINATION OF GDP
- 13. The simple multiplier is the multiplier when the price level is constant. It is equal to 1/[1 - z], where z is the marginal propensity to spend out of national income. Thus the larger z is, the larger is the multiplier. It is a basic prediction of macroeconomics that the simple multiplier, relating £1 worth of increased spending on domestic output to the resulting increase in GDP, is greater than unity. A BASIC MODEL OF THE DETERMINATION OF GDP
- 14. Terminology of Business Cycles
- 15. A trough is characterized by high unemployment and a level of demand that is low in relation to the economy’s capacity to produce. Recovery is characterised by run down equipment being replaced, employment, income and consumer spending all beginning to rise and expectations becoming more favorable. A peak is the top of a cycle. At the peak existing capacity is utilized to a high degree. Recession is defined as a fall in real GDP for two quarters in succession. It is a phase of downturn in economic activity.
- 16. Calculation of average and marginal propensity to consume
- 17. 500 1000 1500 450 450 2000 500 1000 1500 2000 (i). Consumption Function [£ million] Real Disposable Income C S 500 1000 1500 2000 The Consumption and Saving Functions -500 -100 0 250 500 Real Disposable Income (ii). Saving Function [£ million] Note: Initially, at zero income consumers are drawing down on existing savings / assets .
- 18. Consumption and savings schedules (£millions)
- 19. The consumption and saving functions Both consumption and saving rise as disposable income rises. Line C relates desired consumption to disposable income. Its slope is the marginal propensity to consume (MPC). Saving is all disposable income that is not spent on consumption. The relationship between disposable income and desired saving is shown by line S.
- 20. The consumption and saving functions Its slope is the marginal propensity to save (MPS). Any given amount of disposable income must be accounted for by consumption plus saving. Consumption and saving schedules (Table) show the numerical values of desired consumption and saving at each level of income, and correspond to the C and S lines in the figure.
- 21. The aggregate spending function in a closed economy with no government (£million)
- 22. 1000 2000 3000 4000 1000 2000 3000 Real National Income Function [GDP] [£m] 350 An Aggregate Expenditure Function 4000 5000 AE 5000
- 23. An aggregate expenditure function The aggregate expenditure function relates total desired expenditure to national income. Here desired expenditure is the sum of desired consumption and desired investment. It is assumed that desired investment is £250 million while consumption is £100 million plus 0.8 times income. So when income is zero there is autonomous expenditure of £350 million. The marginal propensity to spend is 0.8.
- 24. The determination of equilibrium GDP (£million)
- 25. 0 1000 2000 1000 2000 3000 Real National Income [GDP] [£m] 350 [i]. An Aggregate Expenditure Function[AE = Y] 3000 450 450 [AE = Y] S I [ii]. Saving Function[S = I] Real National Income [GDP] [£m] 3000 2000 1000 500 -100 -500 0 Desired saving (£m) 250 Y0 Equilibrium GDP Y0 E0
- 26. GDP is in equilibrium where aggregate desired expenditure (AE) equals national output. In the figure equilibrium GDP occurs at E0 where AE intersects the 450 line. If GDP is below Y0 desired AE will exceed national output and production will rise. Equilibrium GDP
- 27. If GDP is above Y0 desired AE will be less than national output and production will fall. When saving is the only withdrawal and investment is the only injection, the equilibrium level of GDP is also that where saving equals investment. Equilibrium GDP
- 28. 0 450 AE = Y Real National Income [GDP] The Simple Multiplier
- 29. Y0 0 E0 AE0 e0 450 AE = Y Real National Income [GDP] The Simple Multiplier
- 30. Y0 0 AE1 Y1 E0 E1 AE0 e1 e’1 e0 450 a Y A AE = Y Real National Income [GDP] The Simple Multiplier
- 31. The simple multiplier An increase in the autonomous component of desired aggregate expenditure increases equilibrium GDP by a multiple of the initial increase. The initial equilibrium is at E0, where AE0 intersects the 450 line. Here desired expenditure equals national output.
- 32. The simple multiplier An increase in autonomous expenditure of A then shifts the AE function up to AE1. Because desired spending is now greater that output, production and GDP will rise. Equilibrium occurs when GDP rises to Y1. Here desired expenditure e1 equals output Y1.
- 33. The multiplier – A numerical example
- 34. The multiplier – A numerical example
- 35. A numerical example of the multiplier Assuming that the marginal propensity to spend out of national income is 0.8 and there is an autonomous expenditure increase of £100m. National income and output initially rises by £100m.
- 36. A numerical example of the multiplier Those receiving £100m in income then spend £80m. This £80m of income leads to further spending of £64m. This £64m of income lead to a further increase in spending of £51.2m. If we carry on this process it will converge to an extra income and output totalling £500m. The multiplier in this case is 5.
- 37. A BASIC MODEL OF THE DETERMINATION OF GDP The macroeconomic problem: inflation and unemployment Models of the short-term determination of GDP explain why actual GDP deviates from potential GDP. Actual GDP above potential can be associated with inflation, while actual GDP below potential is associated with unemployment and lost output.
- 38. A BASIC MODEL OF THE DETERMINATION OF GDP Key Assumptions For simplicity we aggregate all industrial sectors into one, so the economy produces only one type of output good. We explain GDP determination through the major expenditure categories: private consumption, investment, government consumption, and net exports.