[R-sig-ME] nlme Fixed Variance Function

Agostino Moro agostino.moro99 at gmail.com
Thu Feb 23 18:53:14 CET 2012


Dear R users,

I am trying to fit a gls model and weight my data points using a
VarFixed structure. I have found many examples, but I do not
understand the difference between the following models with varFixed
specified in a different way:

mod<-gls(y~x,weights=varFixed(~1/invsigma)

mod<-gls(y~x,weights=varFixed(~invsigma)

In my case I would simply like to weigh my data points by their
inverse variance.

Any help would be greatly appreciated!

Cheers,

Agostino




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