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Spatial correlation in glmmTMB

2 messages · Highland Statistics Ltd, Ben Bolker

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I suggest trying INLA.

http://www.r-inla.org/


I hope that you have more than 62 observations in total?

Kind regards,

Alain

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Hello,

I would like to ask for help on how to account for spatial correlation in
glmmTMB package.

According to the help page (
https://cran.r-project.org/web/packages/glmmTMB/vignettes/covstruct.html),
I need to create a numFactor object grouping coordinates and a dummy
grouping factor.

mydata$pos <- numFactor(mydata$easting, mydata$northing)## spatial
coordinates
mydata$group <- factor(rep(1, nrow(mydata)))## dummy factor

Regarding to the dummy variable, I have 62 locations in my dataframe. The
dummy variable should be 1 for all observations, or go from 1 to 62?
(Actually I have tried both possibilities. First one give me convergence
problems, second one cracks my R).

I have been trying to run the following negative binomial mixed model:

m1 = glmmTMB(density ~ wave_exposure + (1|location) exp(pos + 0|group),
data= mydata, family= nbinom1, ziformula= ~0) ##

I also tried different covariance structures (gau and mat), but no success
so far.

Any ideas or suggestions here?

Thank you in advance!

Andre.

-- 
Visiting PhD student
School of Ocean Sciences
Bangor University
Menai Bridge, Anglesey, UK




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#
For glmmTMB, if your locations aren't otherwise grouped (e.g. into
distinct sites), then you should use factor(rep(1,62)).  As Alan Zuur
suggests, 62 might be a fairly small sample for estimating spatial
autocorrelation.  If you give us more information about your model (e.g.
post the results of summary(), it might help us diagnose and/or fix your
convergence problems ...

  The mgcv package will also let you fit negative binomial/spatial
models (with a Mat?rn structure, see ?smooth.construct.gp.smooth.spec;
for the random effect, see ?smooth.construct.re.smooth.spec).
On 2019-07-18 6:33 a.m., Highland Statistics Ltd wrote: