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...he semi-variogram for the within-group residuals and add the semi-variogram of the corSpatial element (corGaus in my case) included in my model ... so far no problem. I was surprised, however, to see on the plot of the semi-variogram issued from the Variogram function, (see figure at http://imm.io/3OLe) the low range value (~1600 meters) used in the corGaus structure included in the lme object. When I fitted the same corGaus structure manually or using the fit.variogram function (package gstat) on the data of each group defined in lme, it gaves me ranges between 2050 and 2700 meters (mean 2350 me...

Dears UseRs, In Zuur's book (Mixed effects models and extensions in ecology with R), p 167, it is mentionned that the Variogram function (package nlme) scale the sill to 1. Here is the plot of the semi-variogram given by the Variogram function on my "lme" object. (http://imm.io/3OLe) Note that the semi-variance exceed 1 !! It can probably explain why the Gaussian correlation structure fitted in my "lme" model is strange (curve is probably fitted to the data above 1). See my previous message a few minutes ago untitled "Variogram (nlme) of a lme object - corSpati...