The details about subject = id(center) in the PROC GEE

[Diels_O]

Dear all, I met a question in PROC GEE analysis:

I want to add the center as a random effect to the model:

However, in my data, the ID was an independent on Center. (Refers to ID in each enter was not repeated)

data gee1;
input Center ID group Visit1-Visit4;
datalines;
1 1 1 0 0 0 0
1 2 1 0 0 0 0
1 3 1 1 1 1 1
1 4 0 1 1 1 0
1 5 1 1 1 1 1
1 6 0 0 0 0 0 
2 7 0 1 0 0 1
2 8 1 0 1 0 1
2 10 0 1 1 1 1
2 11 1 0 1 1 0
2 12 1 0 0 1 1
2 13 0 1 1 0 0 
;
data gee1;
set gee1;
Visit=1; Outcome=Visit1; output;
Visit=2; Outcome=Visit2; output;
Visit=3; Outcome=Visit3; output;
Visit=4; Outcome=Visit4; output;
run;
proc print; run;
Proc gee data = work.gee1 desc;
class id visit group(desc) outcome(desc) center;
model outcome = group / dist = binomial link = logit WALD TYPE3;
REPEATED subject = id(center)/ within = visit type = UN CORRW;
run;

And in the example in the https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_gee_examples01.htm,

The ID in each center is the same.

Can I use the reapeated subject = id(center) to input center as random effect?

If not, How Can I adjusted for center?

Sincerely hope I can get you help!

[Diels_O]

Dear all, I met a question in PROC GEE analysis:

I want to add the center as a random effect to the model:

However, in my data, the ID was an independent on Center. (Refers to ID in each enter was not repeated)

data gee1;
input Center ID group Visit1-Visit4;
datalines;
1 1 1 0 0 0 0
1 2 1 0 0 0 0
1 3 1 1 1 1 1
1 4 0 1 1 1 0
1 5 1 1 1 1 1
1 6 0 0 0 0 0 
2 7 0 1 0 0 1
2 8 1 0 1 0 1
2 10 0 1 1 1 1
2 11 1 0 1 1 0
2 12 1 0 0 1 1
2 13 0 1 1 0 0 
;
data gee1;
set gee1;
Visit=1; Outcome=Visit1; output;
Visit=2; Outcome=Visit2; output;
Visit=3; Outcome=Visit3; output;
Visit=4; Outcome=Visit4; output;
run;
proc print; run;
Proc gee data = work.gee1 desc;
class id visit group(desc) outcome(desc) center;
model outcome = group / dist = binomial link = logit WALD TYPE3;
REPEATED subject = id(center)/ within = visit type = UN CORRW;
run;

And in the example in the https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_gee_examples01.htm,

The ID in each center is the same.

Can I use the reapeated subject = id(center) to input center as random effect?

If not, How Can I adjusted for center?

Sincerely hope I can get you help!

[StatDave · Accepted solution]

The GEE model does not use random effects, so you cannot add a random effect for CENTER in your PROC GEE model. If observations are considered correlated within IDs and observations from different IDs are considered uncorrelated, then SUBJECT=ID is what you need. And you are already adjusting for CENTER by including it as an effect in the MODEL statement.