how to make reference variable in Proc logistic

[SSin]

I am running Proc Logistic and it works perfectly fine. However, I would like to define reference level. For example, I have a categorical variable of "Race" with 4 levels ; Chinese, Malay, Indian and Others. I would like to make SAS reads "Chinese" as my reference but now SAS is reading "Others" as my reference. I am using this statement. 

proc logistic data=WORK.IMPORT3 descending; /* SAS treats the levels of Adenovirus_E in a descending order (high to low)*/ 
   class HDB Sick_Season Race Smoker Service;
   model Adenovirus_E= HDB Sick_Season Race HDB*Race Smoker Service age_at_date_of_reprot_sick  / expb;
run;

 Please let me know how to solve this? Many thanks!

[FreelanceReinh · Accepted solution]

Hi @SSin,

Use the REF= option after the variable name in the CLASS statement, e.g.

class HDB Sick_Season Race(ref='Chinese') Smoker Service;

[SSin]

Many thanks!

[DWilson]

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@SSin wrote:

I am running Proc Logistic and it works perfectly fine. However, I would like to define reference level. For example, I have a categorical variable of "Race" with 4 levels ; Chinese, Malay, Indian and Others. I would like to make SAS reads "Chinese" as my reference but now SAS is reading "Others" as my reference. I am using this statement. 

proc logistic data=WORK.IMPORT3 descending; /* SAS treats the levels of Adenovirus_E in a descending order (high to low)*/ 
   class HDB Sick_Season Race Smoker Service;
   model Adenovirus_E= HDB Sick_Season Race HDB*Race Smoker Service age_at_date_of_reprot_sick  / expb;
run;

 Please let me know how to solve this? Many thanks!

---

Use the ref= option on the class statement, like this:

proc logistic data=one;
class x (ref='1');
model y=x;
run;