[R] Generalized Estimating Functions

[Frederico Zanqueta Poleto]

  Hi,

I'm trying to fit a marginal model via GEE but I'm getting strange 
results and few problems.
If I set the working correlation as exchangeable I'm getting the same 
fitting when I set as independent. Comparing to SAS results it shouldn't 
happen.
If I try to use another working correlation (like AR-M or stat_M_dep), R 
just exits without giving any error message.
Another doubt is how R estimates the scale parameter for Poisson? I get 
1.36 in R, 1.25 in SAS (estimation by the square root of DEVIANCE/DOF) 
and 1.17 (estimation by the square root of Pearson's Chi-Square/DOF).
I'm using R 1.4.1 but all the problems apply for S-Plus 2000 too.
I hope anybody can help me.

Sincerely,

-- 
Frederico Zanqueta Poleto
fred at poleto.com - ICQ# 4129787 


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