SAS regresses missing values - sas

Question

For some reason when SAS does proportional hazards regression it is including those observations that are specified as . as a group in the results. I suspect it has something to do with how I created my variable (and that SAS thinks my numeric variables are characters) but I can't figure out what I did wrong. I am using SAS 9.4
data final; set final;
if edu_d = 'hs less' then edu_regress = 1;
else if edu_d = 'hs' then edu_regress = 1;
else if edu_d = 'some college' then edu_regress = 2;
else if edu_d = 'college plus' then edu_regress = 3;
else if edu_d = 'missing' then edu_regress=.;
run;
Then I run my regression:
proc phreg data=final;
class edu_regress;
model fuptime*dc(0)=edu_regress/rl;
run;
And the output is as follows:
edu_regress . 1 0.10963 0.12941 0.7177 0.3969 1.116 0.866 1.438
edu_regress 1 1 0.22514 0.10949 4.2278 0.0398 1.252 1.011 1.552
edu_regress 2 1 0.21706 0.11410 3.6190 0.0571 1.242 0.993 1.554
Where . is a category instead of treated as missing.
I'm sure I'm making a rookie mistake but I just can't figure it out.

Answer 1

I would clear your output, and re-run the code, and check the log and output.
As I read the docs, to get missing values treated as a category you would need to have /missing on your CLASS statement, which you do not have in the code shown. Without that, I think missing values should be automatically excluded.
When I run PHREG with a CLASS variable that has missing values, I get a note in the log about observations being deleted due to missing values, and the output shows that the number of observations used is less than the number of observations read.

Answer 2

If SAS thinks edu_regress is character, that's possible if it already was on the dataset as character. This is one reason not to do data x; set x; and instead make a new dataset. You should see notes in the datastep when you run it the way you have now regarding numeric to character conversion, if this is indeed the problem.
Anyway, one way to adjust this is to use CALL MISSING. It sets a variable to missing correctly regardless of the type.
data final;
set final;
if edu_d = 'hs less' then edu_regress = 1;
else if edu_d = 'hs' then edu_regress = 1;
else if edu_d = 'some college' then edu_regress = 2;
else if edu_d = 'college plus' then edu_regress = 3;
else if edu_d = 'missing' then call missing(edu_Regress);
run;