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Econometrics I Summer 2011/2012 Course Guarantor : prof. Ing. Zlata Sojková, CSc ., Lecturer : Ing. Martina Hanová, PhD. . Econometrics Assumptions of Classical Linear Regression Model. 7) Calculation of standardized coefficients or beta coefficients βj adj . = βj * R 2 *100 [%].
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Econometrics I Summer 2011/2012 Course Guarantor: prof. Ing. Zlata Sojková, CSc., Lecturer: Ing. Martina Hanová, PhD. EconometricsAssumptions of Classical Linear Regression Model
7) Calculation of standardized coefficients or beta coefficients βjadj. = βj * R2 *100 [%]
Assumption of Ordinary Least Squares • Remember that OLS is not the only possible estimator of the βs • ButOLS is the best estimator under certain assumptions…
Model is linear in parameters Assumption 1
E(Y | Xi ) = β1 + β2Xi LRM E(Y | Xi) = β1 + β2 X2i E(Y | Xi ) = β1 + β22XiNRM Linear regression model
Zeromeanvalueofdisturbances - ui. ASSUMPTION 2
Equalvarianceofdisturbences - ui Errors have constant variance “homoskedasticity” Errors have non-constant variance “heteroskedasticity” ASSumption 3
No autocorrelationbetweenthedisturbances The data are a random sample of the population ASSumption4
Construction of var-cov matrix: vector ei * transpose vector ei variationcovariancematrix
Zerocovariancebetweenui and Xi ASSumption5
thenumberof >= thenumberof observationsexplanatoryvariables ASSumption6
The errors are normally distributed Normal Probability Plot Assumption 7