[R-sig-eco] GAM - Cyclic splines

[SamiC]

Hi,

I am trying to use cyclic splines in gamm4 to model year day.  I have data
running from say day 6 to day 300 but I want to specify the outer limits of
the data are at 0 and 366.  I dont want to fix the inner position of the
knots however (I allow for a total of 5 knots).  Is there a way to do this? 
I also have other explanatory variables in the model that are not cyclic.

Example:
Model<-gamm4(Y~s(X1,fx=FALSE,k=5,bs="cc")+s(X2,fx=FALSE, k=5,
bs='cr')+offset(log(X3)),random=~(1|X4),data=data,family=poisson)

Finally when I try to plot the predictions on the response scale the values
predicted at 0 and 366 are vastly different and do not match, as when
outputs using plot(Model$gam,se=TRUE).

Any help on this would be much appreciated.

Cheers

Sam



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