I am testing heteroscedasticity for Linear Regression Model. I have a categorical independent variable i.e. mealcat having three categories -
1,2 and 3. I am using this equation - api00 = a1 + b1*yr_rnd + b2*mealcat + b3*some_col.
Should i create dummy variables (k-1 categories) for a categorical variable and then change the equation? Is there any CLASS statement to classify categorical variable in PROC MODEL?
api00 = a1 + b1*yr_rnd + b2*mealcat1 + b3*mealcat12 + b4*some_col
Is the above equation correct?
Detailed Code -
proc model data= bhalla.GLMSELECT;
parms a1 b1 b2 b3;
api00 = a1 + b1*yr_rnd + b2*mealcat + b3*some_col;
fit api00 / white pagan=(1 yr_rnd mealcat some_col)
out=resid1 outresid;
run;
quit;
