Hi all,

I have a dataset in which the output Y is observed on two groups of
patients (treatment factor T with 2 levels).

Every subject in each group is observed three times (not time points but
just technical replication).

I am interested in estimating the treatment effect and take into account
the fact that I have repeated measurements for every subject.

If I do this with repeated measures ANOVA (in which the patient is
considered a random effect) I got the following results:

 

              library(nlme)

data<-read.table("http://146.9.88.18/uploads/dataGEE.txt",header=TRUE)

       res<-lme(Y~T,random=~1|P,data=data)

       summary(res)

 

So the p-value for significance of the treatment effect is 0.069.

I would like to use also as a variant analysis a Generalized Estimation
Equation Model, like 

                library(gee)

                summary(gee(Y~T,id=P,data=data))

 

Questions:

A) Is the gee approach suitable in this case with the model formulae I
use?

B) Can I obtain a p-value for the fixed effect T ?

 

Thanks,

 

Laurentiu Tarca

 

 


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