[R] Error in GEE model fit
davamaillist at gmail.com
Sat Sep 20 10:50:27 CEST 2008
I would like to fit a GLM model with GEE on clustered data.
I tried to use gee in the GEE package on a twin data set. All cluster
are of size 2. I removed the missing data and ordered by IDENTIF2 first.
mod.pc <- gee(Y ~ X1 + X2 , id = IDENTIF2, family = binomial, corstr
= "unstructured", data = na.omit(df))
gives the following result :
Beginning Cgee S-function, @(#) geeformula.q 4.13 98/01/27
running glm to get initial regression estimate
(Intercept) X1M X2Sans AMP X2Stim
-2.7756284 0.4658861 -1.6508288 -1.5059518
Erreur dans gee(Y ~ X1 + X2, id = IDENTIF2, family = binomial, corstr
= "unstructured", :
NA/NaN/Inf dans un appel à une fonction externe (argument 2) #
meaning in a call to an external function
De plus : Warning message:
In gee(Y ~ X1 + X2, id = IDENTIF2, family = binomial, corstr =
NAs introduits lors de la conversion automatique # meaning NAs
introduced during the automatic conversion
The regression gives results
with SAS version 8 on the same dataset (results are pretty close from
the results of a naive logistic regression).
I tried to change the explanatory variables (X1 alone, X2 alone, other
possible explanatory variables : no result).
I do not find where the error comes from. Should I trust the results from SAS ?
Thank you for your help.
Using R2.7.2 and gee version 4.13-13
PS Naive logistic regression give similar results on R and SAS in my case
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