Dear I am analysing my data wit a mixed model. I used SAS but I want to redo the same analysis in R. Here the SAS code and what I wrote in R. It seems to work but the results are not the same. I don't know how to specify the class variable in R or specify the variance matrix. Can you please help me? Thanks Jurgen ## SAS: proc glimmix data=trend method=RSPL; class pid; model mdrfinal (event = '1') = time therapy comment / dist=binary link=logit solution cl; random intercept / subject=pid type=un; run; ## R: model_GLMM<- glmmPQL(mdrfinal ~ time + therapy + comment, data = data, family = binomial, random = ~1| time) summary(model_GLMM) -- View this message in context: http://r.789695.n4.nabble.com/code-for-mixed-model-in-R-tp4416915p4416915.html Sent from the R help mailing list archive at Nabble.com.
code for mixed model in R?
2 messages · jurgen_vercauteren, Ben Bolker
jurgen_vercauteren <jurgen_vercauteren <at> hotmail.com> writes:
I am analysing my data wit a mixed model. I used SAS but I want to redo the same analysis in R. Here the SAS code and what I wrote in R. It seems to work but the results are not the same. I don't know how to specify the class variable in R or specify the variance matrix. Can you please help me? Thanks Jurgen ## SAS: proc glimmix data=trend method=RSPL; class pid; model mdrfinal (event = '1') = time therapy comment / dist=binary link=logit solution cl; random intercept / subject=pid type=un; run; ## R: model_GLMM<- glmmPQL(mdrfinal ~ time + therapy + comment, data = data, family = binomial, random = ~1| time) summary(model_GLMM)
This question would probably get a better reception on the r-sig-mixed-models <at> r-project.org mailing list. I think you want random = ~1|pid , although with an unstructured variance-covariance matrix you may want random=~factor(time)|pid -- keep in mind that's what on the RHS of the bar is a grouping factor, the LHS of the bar is the random effect(s) term. If you do ~1|pid you'll get a compound-symmetry model with positive rho; if ftime is a factor variable and you do ~ftime|pid you'll get an unstructured matrix.