Hi, I have been asked to analyse a survey taken of ~1500 persons at two time points (baseline and baseline + 24 mths) as part of a cohort study. It is unbalanced due to dropout and top up and the waves are unevenly spaced: both T1 and T2 surveys were collected over a 6 month period. The outcome is binary and represents attendance or otherwise at a support service. There are four kinds of support services and respondents can attend any or all of them. My job is to simply determine whether there were differences in attendance by group (race, district) and if the likelihood of attendance of a service in T2 was greater than in T1. Control variables include age and existinghealthissue (yes/no) I am fairly new to this type of modelling having only done various types of survival analysis and clean repeated measures designs to date, so I'm unsure how to specify this in SAS. I understand that PROC GLIMMIX is able to specify binary logistic repeated measures but I get stuck specifying the random effects part and then get confused about whether this is the correct way to answer the question. I have also looked at GEE models which seem more intuitively simple as I have a policy background, however I don't think they will answer the second of my questions. I also wonder whether GLIMMIX is overkill. SAS version 9.4 Example data: ID Time Race District Age existinghealthissue AttSvc1 ID1 T1 1 2 19 1 0 ID1 T2 1 2 19 1 1 ID2 T1 2 1 25 1 1 ID3 T1 1 1 29 0 1 ID3 T2 1 1 29 0 1
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