Hi, Saskia, Have a look at the package gamlss by Mikis Stasinopoulos and Bob Rigby. They also have a comprehensive textbook (plus lots of examples) which you can download from http://www.gamlss.org/.
Cheers, Li -----Original Message----- From: r-sig-ecology-boun...@r-project.org [mailto:r-sig-ecology-boun...@r-project.org] On Behalf Of Saskia Otto Sent: Tuesday, 28 December 2010 11:05 PM To: r-sig-ecology@r-project.org Subject: [R-sig-eco] bootstrapping and 2-dimensional smoothers in GAMs Dear all, I'm currently doing some GAM analysis and would like to include 2-way interactions between my continuous, explanatory variables. I know that for this, I need to include 2-dimensional smoothers but I'm not sure how to include them. For linear models I learned that I should always include the variables that are in the interaction term as main terms, i.e. y = b0 + b1*x + b2*z + b3*xz (usually everybody cites Underwood, 1997) How is it with GAMs if I want to include a 2-dimensional smoother for interactions? In some papers I see the same approach, i.e. y = b0 + s1(x) + s2(z) + s3(x,z). But in some papers I see only models like this: y = a + s(x,z), i.e. only the 2-dimensional smoother. Is there a general rule with GAMs? Also, some of my smoothers have in the models p-values between 0.01 and 0.05. Since p-values in this range should not be trusted it is always advised to do bootstrapping to get better p-values. Does anybody know how to do that? My model looks like this: GAM1 <- gam(cop ~ s(Temp) + s(Sal) + s(Chl a), data = daten.sub) Thanks for your help and a happy new year!! Saskia Otto [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- This email is intended for the addressee(s) named and may contain confidential and/or privileged information. If you are not the intended recipient, please notify the sender and then delete it immediately. Any views expressed in this email are those of the individual sender except where the sender expressly and with authority states them to be the views of the Department of Environment, Climate Change & Water NSW. PLEASE CONSIDER THE ENVIRONMENT BEFORE PRINTING THIS EMAIL _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
