topic Modeling Longitidunal Proportional Data in SAS Health and Life Sciences

Modeling Longitidunal Proportional Data

deleted_user — Sat, 16 Aug 2008 12:38:42 GMT

I am dealing with a problem to model longitudinal proportional data using both GEE (M1) and GLMM (M2). I am not sure if my syntax is correct especially for GEE since most SAS books only cover longitudinal "binary" data. I am even not sure if PROC GENMOD can handle GEE modeling for "repeated proportions". Both proportional and binary data belong to binomial distribution but the former one is in group level while the latter one individual level. Hope any one can share experience or opinion with me.

Thanks

Jacob

===================================
M1: GEE
proc genmod data=dsn;
class ID group;
model num/den = time group / link=logit dist=binomial type3;
repeated subject=ID/type=ar(1);
run;

M2: GLMM
proc glimmix data=dsn;
class ID group;
model num/den = time group / link=logit dist=binomial solution;
random int time/subject=ID type=un;
run;

ID time num den rate group
1 1 4 5 0.8 A
1 2 3 4 0.75 A
1 3 3 3 1 A
2 1 6 10 0.6 B
2 2 5 5 1 B
2 3 8 10 0.8 B
3 1 1 2 0.5 A
3 2 2 5 0.4 A
3 3 3 5 0.6 A

Note that rate = num / den

Re: Modeling Longitidunal Proportional Data

deleted_user — Sun, 17 Aug 2008 02:47:42 GMT

I do not know where is the binary data, it is not 0/1 coded, it multinormal data I think

Re: Modeling Longitidunal Proportional Data

mftuchman — Wed, 20 Aug 2008 14:56:40 GMT

I don't think this is multinomial (you wrote multinormal - I don't know what that is), but he has clearly specified the model correctly. For each class he has the number of trials and the number of observed events, and he is assuming that the number of events is a binomial distribution with probability p_{class}.