A data scientist runs PROC HPLOGISTIC on a binary outcome in SAS. Which statement correctly sets the reference level for a CLASS variable named 'Region' to 'West'?
Select an answer to reveal the explanation.
Short Explanation
Here's the deal — you set the reference level by putting REF='West' in parentheses right after the variable name: CLASS Region (REF='West'). The other forms either use the wrong option name or add unnecessary parameterization.
Full Explanation
The correct statement is CLASS Region (REF='West'), because SAS specifies a reference level within a CLASS statement by placing the REF= option in parentheses immediately after the variable name. The statement using CLASS Region / REFERENCE='West' has incorrect syntax, since REFERENCE is not a valid slash option for setting the reference level. The statement using CLASS Region (REFERENCE='West') / PARAM=REFERENCE uses the wrong option name, because the reference-level option is REF=, not REFERENCE=, and it also adds an unnecessary PARAM= option. The statement using CLASS Region (REF='West') / PARAM=EFFECT uses REF= correctly, but it adds an unnecessary PARAM= option that changes parameterization; the minimal correct answer is simply CLASS Region (REF='West').