A data scientist uses PROC HPREG to fit a polynomial regression with terms up to degree 3. How should the cubic term for variable 'X' be specified in the MODEL statement?
Select an answer to reveal the explanation.
Short Explanation
Here's the deal — you use the power operator, so X**3 specifies the cubic term in PROC HPREG. Multiplication and bar notation create interactions, and POLY() isn't a SAS HPREG option.
Full Explanation
The correct choice is MODEL y = X X2 X3 because in PROC HPREG (and PROC REG), polynomial terms are specified by creating variables or using the power operator . X2 specifies X squared and X**3 specifies X cubed in the MODEL statement. The MODEL y = X XX XX*X option uses multiplication notation, which SAS interprets as interaction terms between separate variables named X, not polynomial powers of the same variable. The MODEL y = X | X | X option uses bar notation, which generates factorial crossing interactions, not polynomial terms. The MODEL y = POLY(X, 3) option uses a POLY() function that does not exist in SAS PROC HPREG.