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Chapter 14

Chapter 14. Aggregate Expenditure. CHAPTER CHECKLIST. Distinguish between induced expenditure and autonomous expenditure and explain how real GDP influences expenditure plans. Explain how real GDP adjusts to achieve equilibrium expenditure. Describe and explain the expenditure multiplier.

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Chapter 14

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  1. Chapter 14 Aggregate Expenditure

  2. CHAPTER CHECKLIST • Distinguish between induced expenditure and autonomous expenditure and explain how real GDP influences expenditure plans. • Explain how real GDP adjusts to achieve equilibrium expenditure. • Describe and explain the expenditure multiplier.

  3. LECTURE TOPICS • A Quick Review and Preview • Expenditure Plans and Real GDP • Equilibrium Expenditure

  4. A QUICK REVIEW AND PREVIEW • The Economy at Full Employment • At full employment, real GDP equals potential GDP and the unemployment rate equals the natural unemployment. • Potential GDP and the natural unemployment rate are determined by real factors and are independent of the price level.

  5. A QUICK REVIEW AND PREVIEW • The quantity of money and money equilibrium determine nominal GDP. • Nominal GDP and potential GDP determine the price level. • So changes in the quantity of money change nominal GDP and change the price level but have no effect on potential GDP in the short run. • [In the long run, the inflation rate may influence growth, but we are focusing on short-run fluctuations now]

  6. A QUICK REVIEW AND PREVIEW • Departures from Full Employment • Aggregate supply and aggregate demand determine equilibrium real GDP and the price level. • Fluctuations in aggregate supply and aggregate demand bring fluctuations around full employment.

  7. A QUICK REVIEW AND PREVIEW • Fixed Price Level • In the aggregate expenditure model, the price level is fixed. This is a simplified version of Keynes’ model which was developed to explain persistent high unemployment. • The model explains: • What determines the quantity of real GDP demanded at a given price level • How changes in that quantity of real GDP at a given price level may occur in the short run.

  8. 14.1 EXPENDITURE PLANS AND REAL GDP • From the circular flow of expenditure and income, aggregate expenditure is the sum of: • Consumption expenditure, C • Investment, I • Government purchases of goods and services, G • Net exports, (X – M) • Aggregate expenditure = C + I + G + (X – M).

  9. 14.1 EXPENDITURE PLANS AND REAL GDP • Planned and Unplanned Expenditures • Suppose: Motorola decides to produce 11 million cell phones in 2001. • Motorola plans to sell 10 million phones and to put 1 million into inventory [inventory change is part of investment which is part of aggregate expenditure]. • People and firms makes their expenditure plans and they decide to buy 9 million phones from Motorola. • Planned expenditure on phones is 10 million (9 million + 1 million), which is less than production of 11 million.

  10. 14.1 EXPENDITURE PLANS AND REAL GDP • Aggregate expenditure equals aggregate income and real GDP. • But aggregate planned expenditure might not equal real GDP because firms might end up with up more or less inventories than planned. • Aggregate planned expenditure is planned consumption expenditure plus planned investment plus planned government expenditure plus planned exports minus planned imports.

  11. 14.1 EXPENDITURE PLANS AND REAL GDP • Firms make their production plans, they pay incomes that equal the value of production, so aggregate income equals real GDP. • Households and governments make their planned purchases and net exports are as planned. • Firms make their planned purchases of new buildings, plant, and equipment, and their planned inventory changes.

  12. 14.1 EXPENDITURE PLANS AND REAL GDP • If aggregate planned expenditure equals GDP, the change in firms’ inventories is the planned change. • If aggregate planned expenditure exceeds GDP, firms’ inventories are smaller than planned. • If aggregate planned expenditure is less than GDP, firms’ inventories are larger than planned. • Notice that actual expenditure, which equals planned expenditure plus the unplanned change in firms’ inventories, always equals GDP and aggregate income.

  13. 14.1 EXPENDITURE PLANS AND REAL GDP • Unplanned changes in firms’ inventories lead to changes in production and incomes. • If unwanted inventories have piled up, firms decrease production, which decreases real GDP. • If inventories have fallen below their target levels, firms increase production, which increases real GDP.

  14. 14.1 EXPENDITURE PLANS AND REAL GDP • Induced Expenditure and Autonomous Expenditure Autonomous expenditure The components of aggregate expenditure that do not change in response to real GDP changes. Autonomous expenditure equals investment plus government purchases plus exports plus the components of consumption expenditure and imports that are not influenced by real GDP.

  15. 14.1 EXPENDITURE PLANS AND REAL GDP Induced expenditure The components of aggregate expenditure that change when real GDP changes. Induced expenditure equals consumption expenditure minus imports (excluding the elements of consumption expenditure and imports that are part of autonomous expenditure). In other words, the parts of consumption expenditure and [negative] imports that do change as a result of changes in real GDP.

  16. 14.1 EXPENDITURE PLANS AND REAL GDP • The Consumption Function • Consumption function • The relationship between consumption expenditure and disposable income, other things remaining the same. • Disposable income is aggregate income (GDP) minus net taxes. • Net taxes are taxes paid to the government minus transfer payments received from the government.

  17. 14.1 EXPENDITURE PLANS AND REAL GDP Figure 14.1 shows a consumption function. Each dot corresponds to a column of the table. Point A shows that autonomous consumption is $1.5 trillion. As disposable income increases, consumption expenditure increases—induced consumption.

  18. 14.1 EXPENDITURE PLANS AND REAL GDP Along the 45° line, consumption expenditure equals disposable income. 1.When the consumption function is above the 45° line, saving is negative (dissaving occurs).

  19. 14.1 EXPENDITURE PLANS AND REAL GDP 3.At the point where the consumption function intersects the 45° line, all disposable income is consumed and saving is zero. 2.When the consumption function is below the 45° line, saving is positive.

  20. Change in consumption expenditure MPC = Change in disposable income 14.1 EXPENDITURE PLANS AND REAL GDP • Marginal Propensity to Consume • Marginal propensity to consume (MPC) is the fraction of a change in disposable income that is spent on consumption.

  21. 14.1 EXPENDITURE PLANS AND REAL GDP Figure 14.2 shows how to calculate the marginal propensity to consume. 1. A $2 trillion change in disposable income brings 2.A $1.5 trillion change in consumption expenditure, so... 3. The MPC is $1.5 trillion ÷ $2.0 = 0.75.

  22. 14.1 EXPENDITURE PLANS AND REAL GDP • Other Influences on Consumption • Major factors that influence planned consumption are: • Disposable income • Real interest rate • The buying power of money • Expected future disposable income • Demographic structure of the population

  23. 14.1 EXPENDITURE PLANS AND REAL GDP • A change in disposable income leads to a change in consumption expenditure and a movement along the consumption function. • A change in any other influence on planned consumption shifts the consumption function. • For example, • When the real interest rate decreases, or the buying power of money increases, or expected future income increases, consumption expenditure increases. • When the real interest rate increases, or the buying power of money decreases, or expected future income decreases, consumption expenditure decreases.

  24. 14.1 EXPENDITURE PLANS AND REAL GDP Figure 14.3 shows shifts in the consumption function. 1.A fall in the real interest rate or an increase in either the buying power of money or expected future income increases consumption expenditure and shifts the consumption function upward from CF0 to CF1.

  25. 14.1 EXPENDITURE PLANS AND REAL GDP 2.A rise in the real interest rate or a decrease in either the buying power of money or expected future income decreases consumption expenditure and shifts the consumption function downward from CF0 to CF2.

  26. 14.1 EXPENDITURE PLANS AND REAL GDP • Imports and GDP • Consumption expenditure is one major component of induced expenditure, imports are the other. • In the short run, the factor most influencing the quantity of imports is U.S. real GDP. • The marginal propensity to import is the fraction of an increase in real GDP that is spent on imports. • The marginal propensity to import equals the change in imports divided by the change in real GDP that brought it about.

  27. 14.2 EQUILIBRIUM EXPENDITURE • Aggregate Planned Expenditure and GDP • Consumption expenditure increases when disposable income increases. • Disposable income equals aggregate income — GDP — minus net taxes, so disposable income and consumption expenditure increase when GDP increases. • We use this link between consumption expenditure and GDP to determine equilibrium expenditure.

  28. 14.2 EQUILIBRIUM EXPENDITURE Figure 14.4 shows the AE curve. Aggregate expenditure (AE) is the sum of investment (I), government purchases (G), exports (X), consumption expenditure (C) minus imports (M).

  29. 14.2 EQUILIBRIUM EXPENDITURE • Equilibrium Expenditure • Equilibrium expenditure is the level of aggregate expenditure when aggregate planned expenditure equals real GDP. • Equilibrium expenditure equals the real GDP at which the AE curve intersects the 45° line.

  30. 14.2 EQUILIBRIUM EXPENDITURE Figure 14.5 shows equilibrium expenditure. 1. When aggregate planned expenditure exceeds real GDP, an unplanned decrease in inventories occurs. 2. When aggregate planned expenditure is less than real GDP, an unplanned increase in inventories occurs.

  31. 14.2 EQUILIBRIUM EXPENDITURE Figure 14.5 shows equilibrium expenditure. 3. When aggregate planned expenditure equals real GDP, there are no unplanned inventory changes and real GDP remains at equilibrium expenditure.

  32. 14.2 EQUILIBRIUM EXPENDITURE • Convergence to Equilibrium • At equilibrium expenditure, production plans and spending plans agree, and there is no reason to change production or spending. • But when aggregate planned expenditure and actual aggregate expenditure are unequal, production plans and spending plans are misaligned, and a process of convergence toward equilibrium expenditure occurs. • Throughout this convergence process, real GDP adjusts.

  33. 14.2 EQUILIBRIUM EXPENDITURE • Back at Motorola • Recall that in 2001 Motorola had unwanted inventories. So in 2002, Motorola cuts production. • Where does the process end? The process ends when expenditure equilibrium is reached. • Equilibrium expenditure is reached because when real GDP changes by $1 aggregate planned expenditure changes by less than $1. When aggregate planned expenditure is less than real GDP, firms cut production and real GDP decreases. • Aggregate planned expenditure decreases, but real GDP decreases by more than planned expenditure [because of induced expenditure changes], so eventually the gap between planned expenditure and actual expenditure closes.

  34. 14.2 EQUILIBRIUM EXPENDITURE • Similarly, when aggregate planned expenditure exceeds real GDP, firms increase production and real GDP increases. • But real GDP increases by more than the increase in planned expenditure [again, because of the induced expenditure changes]. • Eventually, the gap between planned expenditure and actual expenditure is closed. Similarly, when investment increases, aggregate expenditure and real GDP also increase. But the increase in real GDP is larger than the increase in investment, because of induced expenditure increases. The multiplier is the amount by which a change in investment is magnified or multiplied to determine the change that it generates in equilibrium expenditure and real GDP.

  35. 14.3 THE EXPENDITURE MULTIPLIER • The Basic Idea of the Multiplier • The initial increase in investment led to an even bigger increase in aggregate expenditure because it induced an increase in consumption expenditure. • The multiplier determines the magnitude of the increase in equilibrium aggregate expenditure that results from an increase in investment or another component of autonomous expenditure. • Consumption expenditure decisions, imports, and taxes that open a gap between disposable income and real GDP all influence the multiplier.

  36. Figure 14.6 illustrates the multiplier. 1.A $0.5 trillion increase in investment shifts the AE curve upward by $0.5 trillion from AE0 to AE1. 2.Equilibrium expenditure increases by $2 trillion from $9 trillion to $11 trillion. 3.The increase in equilibrium expenditure is 4 times the increase in autonomous expenditure, so the multiplier is 4

  37. Change in equilibrium expenditure Multiplier = Change in autonomous expenditure 14.3 THE EXPENDITURE MULTIPLIER • The Size of the Multiplier • The multiplier • The amount by which a change in autonomous expenditure is multiplied to determine the change in equilibrium expenditure that it generates. • That is,

  38. 14.3 THE EXPENDITURE MULTIPLIER • Why Is the Multiplier Greater Than 1? • The multiplier is greater than 1 because an increase in autonomous expenditure induces an increase inaggregate expenditure in addition to the increase in autonomous expenditure.

  39. 14.3 THE EXPENDITURE MULTIPLIER • The Multiplier and the MPC • The greater the marginal propensity to consume, the larger is the multiplier. • Ignoring imports and income taxes, the change in real GDP (Y) equals the change in consumption expenditure (C) plus the change in investment (I). • That is, • Y = C + I

  40. 14.3 THE EXPENDITURE MULTIPLIER • Y = C + I But the change in consumption expenditure is determined by the change in real GDP and the marginal propensity to consume. It is: C = MPCY Now substitute MPCY for C in the equation at the top of the screen Y = MPCY + I

  41. I Y = (1 – MPC) 14.3 THE EXPENDITURE MULTIPLIER Now solve for Y as: (1 – MPC) Y = I Rearrange to get

  42. 1 = (1 – MPC) Y Y I I I Y = 1 1 (1 – MPC) = 4. = = 0.25 (1 – 0.75) 14.3 THE EXPENDITURE MULTIPLIER Now, divide both sides of the by the I to give: When MPC is 0.75, the multiplier is:

  43. 14.3 THE EXPENDITURE MULTIPLIER • Imports and Income Taxes • The multiplier depends, in general, not only on consumption decisions but also on imports and income taxes. • Imports make the multiplier smaller that it otherwise would be because only expenditure on U.S.-made goods and services increases U.S. real GDP. • The larger the marginal propensity to import, the smaller is the change in U.S. real GDP that results from a change in autonomous expenditure.

  44. 14.3 THE EXPENDITURE MULTIPLIER • Income taxes make the multiplier smaller than it would otherwise be. • With increased incomes, income tax payments increase and disposable income increases by less than the increase in real GDP. • Because disposable income is what determines consumption expenditure, the increase in consumption expenditure is less than it would be if income tax payments had not changed.

  45. 14.3 THE EXPENDITURE MULTIPLIER • The marginal tax rate determines the extent to which income tax payments change when real GDP changes. • The marginal tax rate is the fraction of a change in real GDP that is paid in income taxes—the change in tax payments divided by the change in real GDP. • The larger the marginal tax rate, the smaller is the change in disposable income and real GDP that results from a given change in autonomous expenditure.

  46. Y I 1 = (1 – Slope of AE curve) 14.3 THE EXPENDITURE MULTIPLIER • The marginal propensity to import and the marginal tax rate together with the marginal propensity to consume determine the multiplier. • Their combined influence determines the slope of the AE curve. • The general formula for the expenditure multiplier is:

  47. Another way to put this is, • the expenditure multiplier is one divided by [the marginal propensity to spend on US-produced output out of real GDP] • [the slope of the AE curve is the marginal propensity to spend on US-produced output out of real GDP – think about it.]

  48. 14.3 THE EXPENDITURE MULTIPLIER Figure 14.7 shows the multiplier and the slope of the AE curve. With no imports and income taxes, the slope of the AE curve equals the marginal propensity to consume, which in this example is 0.75. A $0.5 trillion increase in autonomous expenditure increases real GDP by $2 trillion—the multiplier is 4.

  49. 14.3 THE EXPENDITURE MULTIPLIER With imports and income taxes, the slope of the AE curve is less than the marginal propensity toconsume. In this example, the slope of the AE curve is 0.5. A $0.5 trillion increase in autonomous expenditure increases real GDP by $1 trillion—the multiplier is 2.

  50. 14.3 THE EXPENDITURE MULTIPLIER Business-Cycle Turning Points The forces that bring business-cycle turning points are the swings in autonomous expenditure such as investment and exports. The mechanism that gives momentum to the economy’s new direction is the multiplier.

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