Hi, I am trying to fit a smoothing model where there are three dimensions over which I can smooth (x,y,z). I expect interactions between some, or all, of these terms, and so I have set up my model as
mdl <- gam(PA ~ s(x) + s(y) + s(z) + te(x,y) + te(x,z) + te(y,z) + te(x,y,z),...) I have recently read about the ti(), "tensor product interaction smoother", which takes care of these interaction terms elegantly and does the nesting properly. The help file says "This is much better than attempting the same thing with ‘s’or ‘te’ terms representing the interactions (although mgcv does not forbid it)." There is a 2D example there also. But I don't understand how I should set this up for my 3D example. Do I simply replace the te's above with ti? Or is there more to it than that? Does anyone have experience with this, and can explain how I should do it properly? Mark ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
