[R] New family for gam in the mgcv library

[Eva Cantoni]

Hi!

I'm using R 2.0.1 on a Sun, with mgcv library version 1.3-1.

I would like to implement a new family for the function gam in mgcv 
(truncated Poisson family as defined in Barry & Welsh (2002), Ecological 
Modelling).

I therefore defined a family function with all the necessary components 
(linkfun, linkinv, variance, etc). But then I run into problems because 
my link function is not a standard one, and fix.family.link() and 
fix.family.var() (called by gam.outer) won't work. As I understand, the 
purpose of these two functions is to modify families so to add a "dvar" 
component and a "d2link" component, necessary for the fitting.

The fix I can imagine (but I didn't try yet) is to add the two extra 
components (dvar and d2link) when defining the new family, and to 
redefine the function gam.outer to avoid the use of fix.family.*.

Does someone have experience with this? Would this be the end of my 
troubles?

Thank you for your help,
Eva Cantoni




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