PROC IMPORT DATAFILE= /Home/Woodwc0/Sasuser.V94/Heterosk.Xlsx

PROC IMPORT DATAFILE="/home/woodwc0/sasuser.v94/heterosk.xlsx"

OUT=woodwc0

DBMS=XLSX

REPLACE;

RUN;

data work.woodwc0;

SET work.woodwc0;

ODS graphics off;

PROC sort;

BY pop;

RUN;

PROC reg;

TITLE 'Engle Curve for Travel Expenditure';

MODEL exptrav = income;

RUN;

OUTPUT OUT=RESFILE RESIDUAL=E;

DATA TWO;

MERGE woodwc0 RESFILE;

BY POP;

LNSQRES = LOG(E**2);

LNPOP = LOG(POP);

RECIPOP= 1/POP;

DEXPTRAV = EXPTRAV/POP;

DINCOME = INCOME/POP;

RUN;

COMMENT 'Do not run all these tests in doing your assessment';

COMMENT 'Use discretion and run only the ones that are called for';

PROC REG;

TITLE 'Residual regression for Park test';

MODEL LNSQRES = LNPOP;

RUN;

PROC REG;

TITLE 'Estimation of transformed model';

MODEL DEXPTRAV = RECIPOP DINCOME /NOINT;

RUN;

OUTPUT OUT=RESFILE2 RESIDUAL=DE;

DATA THREE;

MERGE TWO RESFILE2;

BY POP;

LNSQDE = LOG(DE**2);

RUN;

PROC REG;

TITLE 'Residual regression for Park test on transformed equation';

MODEL LNSQDE = LNPOP;

RUN;

PROC REG;

TITLE 'Inherently per-capita model';

MODEL DEXPTRAV = DINCOME;

RUN;

OUTPUT OUT=RESFILE3 RESIDUAL=D2E;

DATA FOUR;

MERGE THREE RESFILE3;

BY POP;

LNSQD2E = LOG(D2E**2);

RUN;

PROC REG;

TITLE 'Residual regression for Park test on inherently per-capita equation';

MODEL LNSQD2E = LNPOP;

RUN;

PROC MODEL;

TITLE 'White Test for Heteroskedasticity';

PARMS B0 B1;

exptrav = B0 + B1*income;

FIT exptrav /WHITE;

RUN;

PROC MODEL;

TITLE 'Refitting with White Standard Errors';

PARMS B0 B1 B2;

exptrav = B0 + B1*income;

FIT exptrav /GMM KERNEL=(BART,1,0);

INSTRUMENTS income;

RUN;

Engle Curve for Travel Expenditure

The REG Procedure

Model: MODEL1

Dependent Variable: EXPTRAV EXPTRAV

Residual regression for Park test

The REG Procedure

Model: MODEL1

Dependent Variable: LNSQRES

Estimation of transformed model

The REG Procedure

Model: MODEL1

Dependent Variable: DEXPTRAV

Note:No intercept in model. R-Square is redefined.

Residual regression for Park test on transformed equation

The REG Procedure

Model: MODEL1

Dependent Variable: LNSQDE

Inherently per-capita model

The REG Procedure

Model: MODEL1

Dependent Variable: DEXPTRAV

White Test for Heteroskedasticity

The MODEL Procedure

White Test for Heteroskedasticity

The MODEL Procedure

OLS Estimation Summary

White Test for Heteroskedasticity

The MODEL Procedure

Refitting with White Standard Errors

The MODEL Procedure

Refitting with White Standard Errors

The MODEL Procedure

GMM Estimation Summary

Refitting with White Standard Errors

The MODEL Procedure