Comparing GAM objects using ANOVA

Dear Fabien,

Is it possible to compare two GAM objects created with the gam() function 
from the mgcv package. I use a slightly modified version of anova.glm() 
named anova.gam(), modified from John Fox (2002). It often gives me some 
aberant responses, especially with "F" test. I use a quasibinomial model 
and scale (dispersion) is calculated and used in the calculation of the F 
value. Does someone already tried this or does someone knows if all this 
is theoretically possible ?

(Your reference is probably to the anova.gam function in the script file 
for the on-line appendix on nonparametric regression to my R and S-PLUS 
Companion to Applied Regression.)

I don't have specific information about your question, but can provide some 
background: Hastie and Tibshirani, Generalized Additive Models (Chapman and 
Hall, 1990), discuss analysis of variance and analysis of deviance 
procedures for GAMs, providing a heuristic justification and some 
simulation evidence. You'll find discussion of the subject on pages 65-67, 
155-156, and 292-294.

I hope that this helps,
  John


-----------------------------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox
-----------------------------------------------------

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._