[R-sig-ME] varFixFact

Gang Chen gangchen at mail.nih.gov
Tue Jul 22 22:50:26 CEST 2008

I have trouble figuring out what is attribute "varFixFact" in  
component "fixDF" of a lme object. Using the data Rail in nlme as an  

 > library(nlme)
 > flme <- lme(travel ~ 1, data=Rail, random = ~1 | Rail)
 > attr(flme$fixDF, "varFixFact")
[1,] 10.17104

I couldn't find any information how this number of 10.17104 is  
calculated through googling, but is this somehow related to the  
covariance matrix of the fixed effects?

If I run lmer from lme4 on the same data,

 > library(lme4)
 > flmer <- lmer(travel ~ 1 + (1|Rail), data=Rail)

how can I obtain this attribute in lme based on the slots of an lmer  
object, flmer?

Thank you,

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