1. Lecture 5: Macroeconomic Model
Dr. Rajeev Dhawan
Director
Given to the
EMBA 8400 Class
South Class Room #600
February 2, 2007

2. Important Macro Lessons To Be Learnt Today
GDP cannot grow beyond its potential in the long run
Loose Monetary Policy can create only a short-run stimulus in GDP. In long-run it only creates inflation! Net-Net money growth determines inflation
Government spending can create only a short-run stimulus in GDP. In the long-run it leads to a rise in the real interest rate with no gain in GDP but higher deficits
Balanced budget spending just redistributes the share of GDP attributed to consumption & government spending

3. ~Typical Macro-Model~
price
level lag 1
world
interest
rate
IMPORTS
world
GDP
inflation
lag 1
world
price
EXPORTS
EXCHANGE RATE
PRICE
LEVEL
NET
EXPORTS
money
INTEREST RATE
INFLATION
government
INVESTMENT
REAL GDP
EXPECTED
INFLATION
UNEMPLOYMENT
CONSUMPTION
DISPOSABLE INCOME
tax
rate
TAX REVENUES
POTENTIAL GDP
capital stock
lag 1
investment
lag 1
CAPITAL STOCK
labor force

4. Macroeconomic Model
The Macroeconomic Model simulates the working of the US Economy using explicit equations to model consumption, investment, exports, imports, exchange rate, price level and inflation rate.

5. Classification and Listing of Equations
Accounting Identities:
Real GDP (GDP); Tax Revenues (T)
Disposable Income (YDP), Net Exports (NETEX)
Price Level (P)
Example: Disposable Income (YDP) = GDP – Tax Revenues (T)
Accounting Identities have the following properties:
As forecasting equations, they are PERFECT!
Don’t have parameters to be fitted
No error term
No theoretical disputes about their truth, only about their relevance

6. 2. Behavioral Equations: Consumption (C), Real Interest Rate (R),
Investment (I), Exchange Rate (EXCH),
Exports (EX), Imports (IM),
Inflation (P%)
Example: Consumption (C) = α0 * Disposable income (YDP)
(Where α0 = marginal propensity to consume = )
Behavioral Equations have the following properties:
Estimated parameter values change as behavior changes
Source of all forecasting errors
Theoretical disputes concerning these equations, e.g., are consumers myopic or forward looking?

7. Endogenous and Exogenous Variables
Accounting Identity
Define: A = B + C ……………………(1)
Where B = A/ ………………..…..(2)
and C = 5 (given)
Then equation (1) becomes A = B +5 which using definition of B becomes the following:
A = (A/2) + 5
Thus, A/2 = 5 or A = 10 and using (2) B=5
In the above example, A & B are endogenous variables and C is an exogenous variable
Behavioral Equation

8. Macroeconomic Model The Exogenous Factors in the model are:
GDP Potential which is GDP value at full employment level
Domestic Policy Variables:
Money Supply (M)
Government Spending (G)
Tax Policy (T%)
Rest-of-the-World (ROW) factors such as
Foreign Interest Rate
Foreign Price Level
ROW GDP Potential

9. Model Simulation Approach
State macroeconomic theory as a complete set of algebraic equations.
Estimate/postulate numerical values of all parameters.
Assume initial conditions for the history of all lagged variables.
Assume “base case” values over future time periods for all exogenous variables.
Solve the model under base case assumptions.
Change some of the exogenous variable assumptions.
Solve the model again under alternative assumptions.
Compare model solutions
Base Case and the alternative policy Simulation.

10. Advantages of the Model Simulation Approach
Integrates short run and long run analysis into one coherent story of the dynamic reactions of an economy to macroeconomic policy.
Traces the complete logic of the model, step-by-step, instead of trying to condense model into a two-dimensional diagram, such as IS-LM diagram.
Extends to real-world macroeconomic policy issues.
Same process applies to realistic models of actual economies, such as U.S. forecasting models, oil shocks, or world slowdown.

11. Listing Of Variables in the Model
12 Endogenous Variables
GDP, C, I, EX, IM, NETEX, R, P, YDP, T, EXCH, P%
(requires 12 equations in 12 unknowns)
7 Exogenous Variables
3 Policy Variables: M, G, TAX%
3 ROW Variables:
1 Other Variable:

12. Listing of 12 Equations in the Model
12 Endogenous Variables
One GDP Equation/Accounting Identity
Three Consumption Related Equations
Two Interest Rate and Investment Equations
Accounting Identity
Accounting Identity
Accounting Identity
Behavioral Equation
Behavioral Equation
Behavioral Equation

13. Two Price Inflation Equations
Four Exchange Rate, Export, Import and Net Export Equations
Two Price Inflation Equations
Behavioral Equation
Behavioral Equation
Behavioral Equation
Accounting Identity
Behavioral Equation
Accounting Identity

14. Glossary of Variables

15. Additional Definitions
The model variables are in real terms (except of course the price variable). We need three other variables in nominal terms to complete our understanding. These are like “derived” accounting identities.

16. Econ 101 Rule

17. Econ 101 Rule
“Given the values of exogenous variables for a given economy, if the values of inflation (P%) = 0.00% & nominal exchange rate (EXCH) = 1.00, then the economy is in equilibrium or steady state in such a way that actual GDP is exactly equal to potential GDP”.
Equal

18. Base Case
The Base Case is the state of the economy where for the given values of exogenous variables, the ECON 101 rule applies and the values of endogenous variables solved in the first year remain constant for all subsequent years

19. Base Case
This means that GDP will be equal to its potential value for all the years in the base case.
Inflation will be equal to ZERO percent
And the exchange rate will be at one for all the years

20. Cont…
This also implies that values of all other endogenous variables will also be constant for the subsequent years.
Why? Endogenous variables P and P% from today become the exogenous variables for subsequent years’ endogenous value calculations as seen from equations 11 and 12.

21. Data Table 1

22. Second half of the data Table 1

23. 4 Important Guidelines to Use the Model
Tools/Options/Calculations/Iterations=100
Use Graph Button to Generate New Graphs for the experiment performed
Use Print Button for Printing the Results
To Reset the Model, Press the Base Case Button, and run the model once using the Calculations Button

24. Article: The Fed’s Thermostat WSJ: by: Milton Friedman
To keep prices stable, the Fed must see to it that the quantity of money changes in such a way as to offset movements in velocity and output
Keynes had taught them that the quantity of money did not matter, that what mattered was autonomous spending and the multiplier, that the role of monetary policy was to keep interest rates as low to promote investment and thereby full employment
Inflation, according to this vision was produced primarily by pressures on cost that could best be restrained by direct controls on prices and wages
MV = PY key a good thermostat was there all along