[R-sig-ME] Fitting GLMM to percent cover data with glmmTMB

[Vasco Silva]

 Apologies for eventual cross-posting.

Vasco



Vasco Silva <silvadavasco using gmail.com> escreveu no dia quinta, 29/11/2018
à(s) 21:24:

> Hi,
>
> I am trying to fit a GLMM on percent cover for each plant species:
>
> >str(cover)
> 'data.frame': 100 obs. of  114 variables:
> $ Plot : Factor w/ 10 levels "P1","P10","P2",..: 1 1 1 1 1 3 3 ...
> $ Sub.plot: Factor w/ 5 levels "S1","S2","S3",..: 1 2 3 4 5 1 2 ...
> $ Grazing : Factor w/ 2 levels "Fenced","Unfenced": 1 1 1 1 1 1 1  ...
> $ sp1 : int  0 0 0 1 0 0 1 ...
> $ sp2 : int  0 0 0 0 0 3 3 ...
> $ sp3 : int  0 1 0 0 1 3 3 ...
> $ sp4 : int  1 3 13 3 3 3 0 ...
> $ sp6 : int  0 0 0 0 0 0 0 ...
>  ...
> $ tot  : int  93 65 120 80 138 113 ...
>
> I was wondering whether the GLMM can be fitted with glmmTMB (tweedie
> distribution) and if so, should I use percent cover or percent cover
> converted to relative abundance?
>
> sp1.glmm <- glmmTMB (sp1 ~ Grazing + (1|Plot), data=cover, family=tweedie
> (link ="logit"))
>
> Any advice would be very much appreciated.
>
> Cheers.
>
> Vasco Silva
>
>

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