Dear R-Users: I am trying to find the robust (or sandwich) estimates of the standard error of fixed effects parameter estimates using the package "lmer2". In model-1, I used "robust=TRUE" on the other, in model-2, I used "robust=FALSE". Both models giving me the same estimates. So my question is, does the robust option works in lmer2 to get the robust estimates of the standard error? If anybody could offer me a suggestion I would greatly appreciate it. Thank you.
Model-1: > p.mle<-lmer2(ddimer~race+steroid+psi+sofa+apache + (apache|subject), > method="ML", data=final, robust=TRUE, cluster="id", weights=final$w) > beta=fixef(p.mle) > Vcov=vcov(p.mle, useScale=FALSE) > se=sqrt(diag(Vcov)) > beta (Intercept) race steroid psi sofa apache 5.826489820 -0.001920670 -0.242040171 0.005293996 0.075468340 0.009245152 > se [1] 0.108325229 0.058921371 0.055975547 0.001285687 0.018119089 0.002559902 Model-2: > p.mle<-lmer2(ddimer~race+steroid+psi+sofa+apache + (apache|subject), > method="ML", data=final, robust=FALSE, cluster="id", weights=final$w) > beta=fixef(p.mle) > Vcov=vcov(p.mle, useScale=FALSE) > se=sqrt(diag(Vcov)) > beta (Intercept) race steroid psi sofa apache 5.826489820 -0.001920670 -0.242040171 0.005293996 0.075468340 0.009245152 > se [1] 0.108325229 0.058921371 0.055975547 0.001285687 0.018119089 0.002559902 Best Regards, Sattar ____________________________________________________________________________________ , and more! [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.