Dear R-Help list,
I want to compare gam models including interaction with simpler models.
For interaction models, I used gam(Y~ti(X1) + ti(X2) + ti(X1,X2))
removing the interaction, the models end as Y~ti(X1) + ti(X2)
How those models compare with models with the form Y ~ s(X1) + s(X2)
In my case, the former (i.e. ti() ) have a better AIC value than those with
s().
Should I keep the ti() form or use only the s() form when I have no
interaction ?
Thanks for your help !
Arnaud