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testing nlme models for spatial correlation

Dear Javier,

It looks like you have only one observation for each combination of BLOQUE/
AMBIENTE/ TRATAMIENTO/ SUBMUESTREO. That is an observation level random
effect (OLRE) which doesn't make sense with a Gaussian distribution. The
ORLE and the residual would model the exact same thing. Model2 doesn't make
sense.

Two other problems: BLOQUE has only 3 levels and AMBIENTE and TRAITAMIENTO
are both used in the fixed and the random part. See
http://bbolker.github.io/mixedmodels-misc/glmmFAQ.html#should-i-treat-factor-xxx-as-fixed-or-random.
AMBIENTE and TRAITAMIENTO are rather crossed than nested. See
http://bbolker.github.io/mixedmodels-misc/glmmFAQ.html#nested-or-crossed
and https://www.muscardinus.be/2017/07/lme4-random-effects/

I can't reproduce the error you get on model4. The output seems reasonable,
although it has the same problems as model2.

Your dataset is suitable for the SPDE approach in INLA.

I would recommend that you consult a (local) statistician.

Best regards,

ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium

To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to say
what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of data.
~ John Tukey

2017-08-01 17:03 GMT+02:00 Javier Moreira <javiermoreira at gmail.com>: