Dear Mixed-Models-UseRs,

I am trying to fit linear models using lme and considering the spatial
autocorrelation structure of my data.
I know that the correlation has a half-normal shape, so I use the function
corGaus.

Observations are coming from several surveys, done at various dates
(sometimes several surveys occurred at one date), done during several years
(sometimes several surveys by year).


- I want to consider the spatial correlation that occur between observations
done within EACH survey
- I DO NOT want to consider spatial correlation between observations done
during ALL surveys

I define the spatial correlation structure as:   corGaus(form = ~ X + Y |
Year/Date/Survey)

Is it correct ?


Another point, outside of the function lme, I can define the range applied
in the corGaus function as:
corGaus( range value, form = ~ X + Y | Year/Date/Survey)

But when I include this statement in the lme function, it do not take into
account the range value given and estimate its value.
Is there a way to force the range applied on the corGaus structure used in
lme in order to apply exactly the same autocorrelation structure to all my
models.


Thanks for your help !

Arnaud

P.S.: sorry for cross-posting with the sig-geo list, but users of both lists
may be able to provide help on that subject.

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