[R-sig-ME] How should the model be written in R

[ONKELINX, Thierry]

Dear Petter,

You cannot use Site as random effect because you have to few lewels to get decent variance estimates.

I would go for
lme(Cover~Site+Ditch_block+Tree_cut+year),random=~1|SQuadrant/Transect/Relevee

where SQuadrant is the interaction between Site and Quandrant. So SQuadrant has one level for each unique combination of Site and the two treatments.

Best regards,

Thierry

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
Thierry.Onkelinx at inbo.be
www.inbo.be

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


-----Oorspronkelijk bericht-----
Van: r-sig-mixed-models-bounces at r-project.org [mailto:r-sig-mixed-models-bounces at r-project.org] Namens Petter Hedberg
Verzonden: donderdag 8 december 2011 12:18
Aan: r-sig-mixed-models at r-project.org
Onderwerp: Re: [R-sig-ME] How should the model be written in R

Would the following model be a correct option.

lme(Cover~Site+Ditch_block+Tree_cut+year),random=~1|Site/Quadrant/Transect/Relevee

Best regards, Petter
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