[R] two basic question regarding model selection in GAM

From: spime <sabya23_at_gmail.com>
Date: Fri, 22 Jun 2007 01:18:58 -0700 (PDT)

Qusetion #1

Model selection in GAM can be done by using: 1. step.gam {gam} : A directional stepwise search 2. gam {mgcv} : Smoothness estimation using GCV or UBRE/AIC criterion

Suppose my model starts with a additive model (linear part + spline part). Using gam() {mgcv} i got estimated degrees of freedom(edf) for the smoothing splines. Now I want to use the functional form of my model taking estimated degrees of freedoms in step.gam() {gam} to search a better model.

You know mgcv masks over gam. So i can not use gam after using mgcv. Is there any way to stop mgcv.

Qusetion #2

Suppose i have three models:
M1. GAM with thin plate regression spline(TPRS)
M2. GAM with cubic regression spline(CRS)
M3. GAM with some TPRS and CRS

To choose best model among the three, can i use their GCV/AIC/UBRE criterion?

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Received on Fri 22 Jun 2007 - 08:24:41 GMT

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