Hi All, I was hoping to get some assistance with my SAS code and some questions I have regarding the procedure. I am fairly new to SAS and general linear mixed models. Description of Data: I am interested in examining whether two groups (variable=gs) show differences in scores on a questionnaire measure over time (2 time points). I am also interested in examining whether there are differences in the groups as a function of the time to expected disease onset (var=EYO). Importantly, not all participants have data for the two time points, some only have data for the first time point. Additionally, the groups are nested in families. The scores on the questionnaires can range from 0 to 180. When I plotted the data I found that it is positively skewed and hence, I decided to try a poisson distribution to account for this distribution. SAS Code (version 9.1) Proc glimmix data=lib.cbi_final_long Plots=residualpanel method=laplace; Where time in (1 2); Class id time gs (ref="neg") family; Model cbi_total =time gs EYO time*GS time*EYO gs*EYO gs*time*EYO /dist=poisson link=log solution; Random intercept /subject=family type=UN; Random intercept /subject=id (family) type=UN; lsmeans gs /ilink; store model_1; Run; Questions: (1) My code seems to run. It converges but the log indicates that "at least one element of the gradient is greater than 1e-3".I was wondering whether my code looks appropriate, or are there any outstanding errors? (2) I understand that with proc mixed, I could use the "influence" statement to obtain influence diagnostics to assess for outliers. Is there something similar I can use with proc GLIMMIX? How can I assess whether there are outliers that should be removed from the analysis? (3) I have seen some examples for the repeated statement specifically to include "time" in the last random statement (e.g. Random time /subject=id (family) type=UN;) to account for the fact that not every participated completed both time points. Is this necessary for the random statement and if I am indicating to only analyze time 1 and time 2? (4) I have n=588 participants who completed the questionnaire at time1 and n=342 participants who completed the questionnaire at time2. Is it appropriate that the "number of observations read/used" in the SAS output equals to N= 930 instead of 1176? Thank you very much for your assistance. Best, Tamara
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