Thank you for your response. This is the log including the procsurvey freq procedure and the error message. 686
687 *multivariable logistic analysis*;
688 proc surveylogistic data=school12345;
689 class AGE_T(REF='UNDER 16') GRAD_T(REF='1') sex(ref='MALE') RACE(REF='WHITE/CAUCASIAN') SCHOOL_REGION(REF='NORTHEAST')
690 GRADAVG(REF='A') DAD_EDU(REF='UP TO COLLEGE') MOM_EDU(REF='UP TO COLLEGE') CIG30(REF='YES') ALC30(REF='YES')
690 ! MJ30(REF='YES')/ PARAM=REF;
691 weight weight;
692 model vape30(EVENT='YES') = AGE_T GRAD_T SEX RACE SCHOOL_REGION GRADAVG DAD_EDU MOM_EDU alc30 cig30 mj30;
693 run;
ERROR: Invalid reference value for GRAD_T.
NOTE: The SAS System stopped processing this step because of errors.
NOTE: PROCEDURE SURVEYLOGISTIC used (Total process time):
real time 0.05 seconds
user cpu time 0.05 seconds
system cpu time 0.00 seconds
memory 1997.43k
OS Memory 33704.00k
Timestamp 10/05/2023 11:27:12 AM
Step Count 36 Switch Count 1
Page Faults 0
Page Reclaims 340
Page Swaps 0
Voluntary Context Switches 5
Involuntary Context Switches 0
Block Input Operations 0
Block Output Operations 0
This is my first time completing a project essentially from beginning to end with analysis. Can you explain what you meant by separation of the data with both age and grade? I can change the model and I understand they correlate, just looking for clarification on that statement. @ballardw wrote: Age of students and grade level are highly correlated, grade is practically dependent on age for the majority of students. It is extremely likely than none of your 12 grade students are in the under 16 age group (one of the places I would not be surprised to a zero in proc freq of age vs grade). Similarly you are unlikely to have very few if any grade 8 students that are over 18. So you are getting separation of data with both age and grade in the model. Using only grades 8, 10 and 12 will make the separation even stronger. You probably won't get much of a usable model for both age and school grade level.
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