[R-sig-ME] How to extract num. of observations and groups used in a mixed model using gee package

[David Winsemius]

On Apr 23, 2012, at 12:44 PM, david oseguera montiel wrote:

> Does anyone know how can extract the number of observations and  
> groups used
> in a mixed model with gee package?
> The summary function in gee package does not provide this information.
> e.g.
> data(warpbreaks)
> summary(gee(breaks ~ tension, id=wool, data=warpbreaks,
> corstr="exchangeable"))

Does this address all of those puzzles?

summgee <- summary(gee(breaks ~ tension, id=wool, data=warpbreaks,   
corstr="exchangeable"))
Beginning Cgee S-function, @(#) geeformula.q 4.13 98/01/27
running glm to get initial regression estimate
(Intercept)    tensionM    tensionH
    36.38889   -10.00000   -14.72222
 > names(summgee)
  [1] "call"                "version"              
"nobs"                "residual.summary"
  [5] "model"               "title"                
"coefficients"        "working.correlation"
  [9] "scale"               "error"               "iterations"
 > summgee$nobs
[1] 54

 > summgee$call
gee(formula = breaks ~ tension, id = wool, data = warpbreaks,
     corstr = "exchangeable")
 > summgee$coefficients
              Estimate Naive S.E.   Naive z Robust S.E.  Robust z
(Intercept)  36.38889   3.069434 11.855246    5.774705  6.301428
tensionM    -10.00000   3.910008 -2.557539    7.463905 -1.339781
tensionH    -14.72222   3.910008 -3.765266    3.731952 -3.944912
 > rownames(summgee$coefficients)
[1] "(Intercept)" "tensionM"    "tensionH"

>
> I much appreciate any help,
>
> David Oseguera Montiel
> Phd student Wageningen University
>
> pd. I asked this a few days ago in R-help list and I did not get any  
> answer yet.
>
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David Winsemius, MD
West Hartford, CT