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Message-ID: <CAMS_pxsV08a82SUAku4BVG9VbZfJeHee1iU8VQZUVG1aGWyp3g@mail.gmail.com>
Date: 2012-02-23T17:52:46Z
From: Agostino Moro
Subject: nlme Fixed Variance Function

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