Equation Modeling - Econometric Modeling - Lecture Notes, Study notes of Econometrics and Mathematical Economics

Econometric models are statistical models used in econometric. This modelling tool help economist develop future economy plan for the company. This lecture note discuss important points for understanding Econometric modelling, it includes Equation, Modeling, Problems, Condition, Identification, Form, References

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2011/2012

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THE SAMPLE PROBLEMS
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Equation1:
OrderCondition:
K=6;M=4;G=3
(KM)=64=2
(G1)=31=2
Exactlyidentified
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THE SAMPLE PROBLEMS

3 1 2 3 3

2 3 3 2

1 2 1 2 1

y y y x u

y y x u

y y x x u

1 2 3 1 2 3 3

1 2 3 1 2 3 2

1 2 3 1 2 3 1       

y y y x x x u

y y y x x x u

y y y x x x u

1 1 1 0 0 2 0 1 1 0 0 1

11 32 03 21 12 03    

  y y y x x x

Equation 1: Order Condition: K=6; M=4; G= (K‐M) = 6 ‐4= (G‐1) = 3 ‐1= Exactly identified

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Rank condition:

1 1 1 0 0 2

0 1 1 0 0 1

1 3 0 2 1 0   

 

1 2

1 1  

As this is non‐zero, equation 1 is exactly identified.

Equation 2:

Order Condition: K=6; M=3; G= (K‐M) = 6 ‐3= (G‐1) = 3 ‐1= Over‐identified

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1 1 1 0 0 2

0 1 1 0 0 1

1 3 0 2 1 0   

 

0 0

2 1

As this is zero, equation 3 is not identified. ESTABLISING IDENTIFICATION FROM THE REDUCED FORM

Order condition:

 K  M   G  1 

Rank condition

G* = number of endogenous variables contained in a particular equation.

An equation containing G* endogenous variables is identified if it is possible to construct at least one non‐zero determinant of order (G*‐1) from the reduced form coefficients of the exogenous variables excluded from that particular equation.

3 1 2 3 3

2 3 3 2

1 2 1 2 1 2

3 2

y y y x u

y y x u

y y x x u

   

  

   

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The reduced form for this model is:

3 1 2

2 1 2 3

1 1 2 3 2

y x x

y x x x

y x x x  

Equation 1: Order Condition: K=6;M=4;G= (K‐M) = 6 ‐4= (G‐1) = 3 ‐1= Exactly identified

Rank condition: Excluded endogenous: y (^3) Included exogenous: x 1 , x (^2)

13 G=2, (G‐1)= As both 3 and 1 are non‐zero, equation 1 is exactly identified.

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Equation 3:

Order Condition: K=6; M=4; G= (K‐M) = 6 ‐4= (G‐1) = 3 ‐1= Exactly identified

Rank condition: Excluded endogenous: None Included exogenous: x (^3)

G=3, (G‐1)=

24  12 ^0

Equation 3 is not identified.

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REFERENCES FOR FURTHER READING:

Montgomery, D. C., Peck, E. A., and G. G. Vining: Introduction to Linear Regression Analysis , Wiley India, New York, 2006.

Dielman, Terry E.: Applied Regression Analysis for Business and Economics, PWS-Kent, Boston, 1991.

Draper, N. R., and H. Smith: Applied Regression Analysis, 3d ed., John Wiley & Sons, New York, 1998.

Frank, C. R., Jr.: Statistics and Econometrics, Holt, Rinehart and Winston, New York, 1971.

Goldberger, Arthur S.: Introductory Econometrics, Harvard University Press, 1998.

Graybill, F. A.: An Introduction to Linear Statistical Models , vol. 1, McGraw- Hill, New York,

Greene, William H.: Econometric Analysis, 4th ed., Prentice Hall, Englewood Cliffs, N. J., 2000.

Griffiths, William E., R. Carter Hill and George G. Judge: Learning and Practicing Econometrics, John Wiley & Sons, New York, 1993.

Gujarati, Damodar N.: Essentials of Econometrics, 2d ed., McGraw-Hill, New York, 1999.

Hill, Carter, William Griffiths, and George Judge: Undergraduate Econometrics, John Wiley & Sons, New York, 2001.

Johnston, J.: Econometric Methods, 3d ed., McGraw-Hill, New York, 1984.

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FAQS (FREQUENTLY ASKED QUESTIONS):

  1. For simultaneous equation models a) There must be more than on endogenous variables b) There must be more than on exogenous variables c) There must be more than on parameter to be estimated d) There must be more than on endogenous and exogenous variables
  2. Applying OLS to simultaneous equation results in the parameter being a) Inefficient b) Inconsistent c) With minimum variance d) Inefficient and inconsistent
  3. The simultaneous equation bias a) Refer to bias of the researcher towards using this model b) In the bias in the estimated parameter that disappears when sample size becomes large c) In the bias in the estimated parameter that does not disappears even when sample size becomes large d) Means the error terms are biased positively in small samples
  4. In simultaneous equation model the number equation to be estimated are a) One more than the number of endogenous variables b) Equal to the number of endogenous variables c) Depends on the underlying economic theory d) Equal to the number endogenous and exogenous variables

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SELF EVALUATION TESTS/ QUIZZES

  1. State whether each of the following statements is true or false: a) The method of OLS is not applicable to estimate a structural equation in a simultaneous-equation model. b) In case an equation is not identified, 2SLS is not applicable. c) The problem of simultaneity does not arise in a recursive simultaneous-equation model. d) The problems of simultaneity and exogeneity mean the same thing. e) The 2SLS and other methods of estimating structural equations have desirable statistical properties only in large samples. f) There is no such thing as an R^2 for the simultaneous-equation model as a whole. g) If an equation is exactly identified, ILS and 2SLS give identical results.
  2. Explains following methods briefly: a) Ordinary least squares(OLS) b) Indirect least squares(ILS) c) Two Stage least squares(2SLS)
  3. Consider the following modified Keynesian model of income determination:

Ct = β 10 + β 11 Yt + u (^) 1t

I (^) t = β 20 + β 22 Yt + β 22 Yt− 1 + u2t