I have two separate clinical trial datasets that have the same variables and sites are numbered consecutively for each clinical trial. I have combined both clinical trials into one dataset using the set statement. I also have a flag for each clinical trial. I have a unique subject id that is unique across both clincial trial datasets. I am clustering patients within sites. The sites ids are the same in many cases across both clinical trials. Is that a problem with proc mixed and using siteid as the clustering variable? Does siteid need to be unique in the combined dataset eventhough the patient id is unique? I have a feeling it is, but wanted to confirm.
I used the following code:
proc mixed data=analysisaim1 covtest method=ML order=data;
class siteid;
model chgql=trial racecat cntrycat totcomorbid suppcare ecogb NumPt trtdur/solution ddfm=kr;
random intercept/subject=siteid;
run;
I am using SAS 9.4 TS. Any help you could provide would be greatly appreciated. Thanks.
The side IDs should be unique for the nesting you describe. Easy to handle. First, trial should be listed in the class statement (I can't imagine how trial is a continuous variable). then in the random statement, use subject=siteid(trial);
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