Dear mixed-models useRs,

I made a mixed model of the form

lme(Distance ~ season, random = ~1|yearTagged/tag, correlation =
corAR1(form= ~Time|yearTagged/tag), data = dat)

or

lme(Distance ~ season, random = ~1|yearTagged/tag, correlation =
corARMA(form= ~Time|yearTagged/tag, p=1, q=1), data = dat)

In the AR1 model, the Phi value obtained for the corAR1 structure is 0.
In the ARMA(1,1) model, both Phi1 and Theta1 are equal to 0.

I find this strange. I believed first that it was caused by the fact that
yearTagegd and tag variables were not considered as factor, but it did not
change anything if I convert them to factor.
The temporal autocorrelation is not obvious in the residuals of the model
without a temporal structure included (i.e. without corAR1 or corARMA), but
can I conclude that there is not correlation based on Phi value ?

Thanks for your help,

Arnaud

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