R help - Oct 2007 - Extracting df (degree of freedom) & estfun (estimating function) from model built in lmer or lmer2

Hello R-users:
 
Could you please tell me how can I extract the "df (degree of
freedom)" and "estfun (estimating functions)" for the following
lmer (or lmer2) model?
 
wtd.mixed<-lmer(ddimer~race+steroid+psi+sofa+apache + (1|subject),
method="ML", data=final, cluster="id", weights=w)
 
I tried the following codes:
 
- for the degree of freedom (erorr message in the red):
 
>so <- summary(wtd.mixed)
> so$df[1:6]
NULL
Warning message:
$ operator not defined for this S4 class, returning NULL in: so$df 
 
-for the estimating functions:
psi <- estfun(wtd.mixed)
         Error in estfun(wtd.mixed) : no applicable method for
"estfun"
 
If you could help me in finding these two quantities I would really appreciate
it. NOTE, if it is not possible to find these quantities in lmer or lmer2, I
would greatly appreciate if you could name a function which will provide these
quantities for mixed models.
 
Thank you. 
 
Sattar


       
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