Hi,
I am trying to answer the see if density.km (response) is affected by Direction
(continuous, integer), Layer (nominal with 12 levels) and direction (nominal
with 8 levels). There is an interaction between Layer and Direction.
Platform.field is a list of 9 different platforms and is being treated as a
random effect.
I had previously ran this model without the correlation argument and checked
the residuals in an acf plot which showed a high level of autocorrelation.
I am having issues applying the correlation argument into my model but keep
getting an error message and am not sure what else to try. I should mention
that Direction is being applied as the time covariate because each distance has
an associated time stamp.
G2<-gamm(density.km~f.Layer+direction+s(Distance.A,by=f.Layer),
random=list(Platform.field=~1),corr=corAR1(form=~Distance.A|Platform.field/f.Layer),
family=poisson,data=fish1)
Maximum number of PQL iterations: 20
iteration 1
Error in Initialize.corAR1(X[[2L]], ...) :
covariate must have unique values within groups for "corAR1" objects?
Any help would be appreciated.
Thanks
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