Hi,
I went over the note and tried specifying the repeated statement in PROC GENMOD as mentioned in the following statement in the note
"GEE models for clustered or longitudinal data can be fit by specifying the REPEATED statement in PROC GENMOD and (beginning in SAS 9.4 TS1M2) in PROC GEE........However, a comparative statistic similar to AIC, known as QIC, is provided in PROC GENMOD and PROC GEE....
Some background: I am using proc genmod to calculate the incidence rate ratio for count data, and here is how my data looks like
ID events person-days exposure log person-days
1 2 80 0 4.38
2 0 11 1 2.39
3 11 60 1 4.09
4 19 30 0 3.40
Following is my code and QIC (attached image) from the output.
proc genmod data= mydata descending; class ID exposure (ref='0'); model events= exposure/offset=log persondays dist=poisson link=log type3 ; repeated subject= ID; run;
My questions are:
1. Being a new SAS user, I am not sure if I have specified the repeated statement correctly?
2. In order to use the repeated statement, does my data need to in repeated ID format, where there are multiple observations by each ID? My current data has a number of events and total person-days contributed collapsed for each ID, does the repeated statement apply to this, since the IDs are not repeated?
3. Looking at the QIC, I think the model is a good fit, but I am not too sure.
Please let me know if more clarification is needed.
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