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The Aggregate Expenditures Model The beginning of the study of Macroeconomic Models and Fiscal Policy Please listen to the audio as you work through the slides.

Creative Commons Attribution 4.0 License, Charles Hackner Houston Community College unless otherwise noted CC BY NC

Learning objectives

Students should be able to thoroughly and completely explain:

The Aggregate Expenditure Model, its components, how the components interact.

The recessionary expenditure gap

The inflationary expenditure gap.

Two critical questions in Macroeconomics

What determines the level of GDP, given a nation’s productive capacity?

What causes real GDP to rise in one period and to fall in another?

Our approach here is similar to the way we developed the circular flow model

Start with the private closed economy

No international trade

No government purchases and taxes

Expand it to look at the mixed economy that includes international trade and domestic government spending

Imports and exports

Government purchases and taxes

Aggregate Expenditures Model

Assumptions

A Private Closed Economy

Defer Government & Taxes

Defer Exports and Imports

Real GDP = DI – to simplify the model

If real GDP is $500 Billion, then households receive $500 Billion in DI to consume or save.

Excess Production Capacity & Unemployed Labor Exists

Increased Aggregate Expenditures will increase real output and employment but not raise prices.

Add the Investment decisions of businesses to the Consumptions plans of households

Construct an investment schedule showing planned investment at each possible level of GDP

Planned investment is independent of the level of current DI or real output

Investment Demand & Schedule

Expected rate of return, r, and

real interest rate, i (percents)

Investment

(billions of dollars)

Investment

(billions of dollars)

20

8

20

Real Domestic Product, GDP

(billions of dollars)

I D

Ig

Investment

Demand

Curve

Investment

Schedule

Amount of Investment

forthcoming at each

level of GDP

20

20

Combine the consumption schedule and the Investment schedule to explain:

The equilibrium levels of:

output,

Income, and

Employment

in the private closed economy.

Equilibrium GDP Terminology

Real Domestic Output – definition

The possible levels of real total output the business sector might produce.

Firms will produce $370 Billion of output incurring $370 Billion of costs (wages, rents, etc) only if they believe they can sell the output for $370 Billion.

Aggregate Expenditures Schedule – Shows aggregate consumption and investment expenditures, at each possible output level.

Equilibrium GDP – the level of output where production creates total spending just sufficient to purchase that output

Equilibrium GDP

GDP = C + Ig

At this point there is:

no overproduction, or excess total spending that draws down inventories of goods and prompts increases in the rate of production.

530

510

490

470

450

430

410

390

370

45°

390 410 430 450 470 490 510 530 550

Disposable Income (billions of dollars)

Consumption and Investment (billions of dollars)

C

Ig = $20 Billion

Aggregate

Expenditures

C = $450 Billion

C + Ig

(C + Ig = GDP)

Equilibrium

Point

Equilibrium GDP

GDP below and above equilibrium (disequilibrium) The adjustment process

What if:

GDP below equilibrium level (spending greater than output)

Economy wants to spend higher levels than the levels of GDP (output) the economy is producing.

Buyers would be taking goods off the shelves faster than firms could produce them.

Unintended decline in inventories.

Business adjust by stepping up production which leads to increased employment and total income.

Process continues until equilibrium is restored.

GDP below and above equilibrium (disequilibrium) The adjustment process

What if: GDP below equilibrium level (spending > output)

Economy wants to spend higher levels than the levels of GDP the economy is producing.

Buyers would be taking goods off the shelves faster than firms could produce them.

Unintended decline in inventories.

Business adjust by stepping up production which leads to increased employment and total income.

Process continues until equilibrium is restored.

What if: GDP above equilibrium level

(spending < Output)

Business finds that these levels of output fail to generate the spending needed to clear the shelves of goods.

Inventories build up

Business will cut back on production.

The decline in output would lead to fewer jobs and a decline in total income

Process continues until equilibrium is restored.

28-14

510

490

470

450

430

45°

430 450 470 490 510

Real GDP (billions of dollars)

Aggregate Expenditures (billions of dollars)

Changes in Equilibrium GDP

Increase in

Investment by $5 B

(C + Ig)0

Decrease in

Investment by $5 B

(C + Ig)2

(C + Ig)1

The Multiplier

Effect

(1)

Change in

Income

(2)

Change in

Consumption

(MPC = .75)

(3)

Change in

Saving

(MPS = .25)

Increase in Investment of $5

Second Round

Third Round

Fourth Round

Fifth Round

All other rounds

Total

$ 5.00

3.75

2.81

2.11

1.58

4.75

$ 20.00

$ 3.75

2.81

2.11

1.58

1.19

3.56

$ 15.00

$ 1.25

.94

.70

.53

.39

1.19

$ 5.00

Rounds of Spending

1

2

3

4

5

All

$20.00

15.25

13.67

11.56

8.75

5.00

$5.00

$3.75

$2.81

$2.11

$1.58

$4.75

ΔI=

$5 billion

The Multiplier Effect

Now we add

International Trade to the model

Net Exports

Positive if exports > imports

Negative if imports > exports

Net Exports and Aggregate Expenditures

C + Ig + ( X – M )

Xn = ( X – M )

C + Ig + Xn

International Trade and Aggregate Expenditures

Net Export Schedule – level of net exports at each level of GDP

Net Exports and Equilibrium GDP

Positive Net Exports

Other things equal, positive net exports increase aggregate expenditures and GDP beyond what it would be in a closed economy.

Negative Net Exports

Other things equal, negative net exports reduce aggregate expenditures and GDP below what they would be in a closed economy.

Real

GDP

+5

0

-5

Net Exports Xn

(billions of

Dollars)

Real GDP (billions of dollars)

Aggregate Expenditures

(billions of dollars)

510

490

470

450

430

45°

430 450 470 490 510

Net Exports and Equilibrium GDP

Aggregate

Expenditures

with Positive

Net Exports

C + Ig

Aggregate

Expenditures

with Negative

Net Exports

C + Ig+Xn2

C + Ig+Xn1

Xn1

Xn2

Positive Net Exports

Negative Net Exports

450

470

490

International Economic Linkages

Prosperity Abroad

Raises the level of real output & income in US.

Tariffs on goods imported from US (our exports)

They improve their economy and depress ours

Exchange Rates

Depreciation – price of US goods to them goes down, US exports go up, US imports go down, net exports go up, GDP goes up.

Appreciation

-700 200 150 100 50 0 50 100 150 200 250

Net Exports of Goods

Selected Nations, 2006

Positive Net Exports

Negative Net Exports

Canada

France

Japan

Italy

Germany

United Kingdom

United States

+31

+70

+203

-45

-27

-171

-881

Source: World Trade Organization

change

20

Now we add the Public Sector to the model

Simplifying Assumptions

Government purchases do not affect consumption and investment spending

All taxes are personal

Tax collections are fixed and unrelated to GDP

45°

470 550

Real GDP (billions of dollars)

Aggregate Expenditures (billions of dollars)

Government Spending Effect

C

Government

Spending of

$20 Billion

C + Ig + Xn

C + Ig + Xn + G

$20 Billion Increase

in Government

Spending Yields an

$80 Billion Increase

In GDP

45°

490 550

Real GDP (billions of dollars)

Aggregate Expenditures (billions of dollars)

Lump Sum Tax Effect

$15 Billion Decrease

In Consumption From

a $20 Billion (MPC=.75)

Increase in

Taxes

Cd + Ig + Xn + G

C + Ig + Xn + G

$20 Billion Increase

in Taxes Yields a

$60 Billion Decrease

In GDP – Why?

Recessionary Expenditure Gap

The amount by which actual GDP falls short of full-employment GDP

Recessionary Expenditure Gap

Actual GDP is below full employment GDP

Real GDP (billions of dollars)

Aggregate Expenditures

(billions of dollars)

550

530

510

490

470

45°

490 510 530

AE0 - full employment spending

AE1 –actual

Full

Employment

Recessionary

Expenditure

Gap = $5 Billion

$5 Billion

Gap Yields

$20 Billion

GDP

Change

Inflationary Expenditure Gap

The amount by which an economy’s aggregate expenditures at the full-employment GDP exceed those just necessary to achieve the full-employment level of GDP.

The amount by which actual GDP exceeds full-employment GDP

Inflationary Expenditure Gap

Actual GDP is above full employment GDP

Real GDP (billions of dollars)

Aggregate Expenditures

(billions of dollars)

550

530

510

490

470

45°

490 510 530

AE0 hypothetical spending at full employment

AE2 actual spendinng

Full

Employment

Inflationary

Expenditure

Gap = $5 Billion

$5 Billion

Gap Yields

$20 Billion

GDP

Change

28-28

The Complete Model

GDP and full employment

Multiplier effects

Government spending

Lump sum taxes

Balanced Budget case

Recessionary gap

Policy options

Inflationary gap - Demand pull inflation

Policy options

Limitations of the Model

Does Not Show Price-Level Changes

Ignores Premature Demand-Pull Inflation

Limited Real GDP to the Full-Employment Level

Does not Deal with Cost-Push Inflation

Does not Allow for “Self-correction”

Let’s See What You Know about Macroeconomics so far.

Including the topic of the Aggregate Expenditures Model, please tell us what you know about Macroeconomics.

Step 1 – Construct an outline based on the key concepts of the AE Model (for example) - C, I, G, Xn

Under each element, outline it’s key elements

Etc.

Step 2 – Add content about each of the key points

Step 3 – Review for completeness

Step 4 - Present

The basic macroeconomic relationships introduced a number of key concepts.

Please explain the relationship between income, consumption, savings, and GDP

Please explain the relationship between interest rates, expected rates of return, investment, and GDP

Please explain the concept of the multiplier, including:

What information is required to calculate the spending multiplier

List and explain the 3 different multipliers that we discussed.

Explain how the multiplier works to impact GDP?