hi all, this subject is very intersting for me. I'm using mgcv 0.8-9 with R version 1.7.1. i didn't know that there was an another gam version with package library(gam). Someone can tell me the basics differences between them? I look for an help page on google but i only find "mgcv" help pages.
thanks! yves magliulo, Paris. Le lun 06/12/2004 � 09:09, Jari Oksanen a �crit : > On 6 Dec 2004, at 7:36, Janice Tse wrote: > > > Thanks for the email. I will check that out.... > > > > However when I was doing this : gam(y~s(x1)+s(x2,3), > > family=gaussian, > > data=mydata )it gives me the error : > > > > "Error in terms.formula(formula, data = data) : > > invalid model formula in ExtractVars" > > > > What does it mean ? > > > When Any Liaw answered you (below), he asked you to specify which kind > of 'gam' did you use: the one in standard package 'mgcv' or the one in > package 'gam'. We should know this to know "what does it mean" to get > your error message. If you used mgcv:::gam, it means that you didn't > read it help pages which say that you should specify your model as: > > gam(y ~ s(x1) + s(x2, k=3)) > > Further, it may be useful to read the help pages to understand what it > means to specify k=3 and how it may influence your model. Simon Wood -- > the mgcv author -- also has a very useful article in the R Newsletter: > see the CRAN archive. It may be really difficult to understand what you > do when you do mgcv:::gam unless you read this paper (it is possible, > but hard). Simon's article specifically answers to your first question > of deciding the smoothness, and explains how elegantly this is done in > mgcv:::gam (gam:::gam has another set of tools and philosophy). > > If you happened to use gam:::gam, then you have to look at another > explanation. > > cheers, jari oksanen > > > From: Liaw, Andy [mailto:[EMAIL PROTECTED] > > Sent: Sunday, December 05, 2004 11:34 PM > > To: 'Janice Tse'; [EMAIL PROTECTED] > > Subject: RE: [R] Gam() function in R > > > > Unfortunately that's not really an R question. I recommend that you > > read up > > on the statistical methods underneath. One that I'd wholeheartedly > > recommend is Prof. Harrell's `Regression Modeling Strategies'. > > > > [BTW, there are now two implementations of gam() in R: one in `mgcv', > > which > > is fairly different from that in `gam'. I'm guessing you're > > referring to > > the one in `gam', but please remember to state which contributed > > package > > you're using, along with version of R and OS.] > > > > Cheers, > > Andy > > > >> From: Janice Tse > >> > >> Hi all, > >> > >> I'm a new user of R gam() function. I am wondering how do > >> we decide on the > >> smooth function to use? > >> The general form is gam(y~s(x1,df=i)+s(x2,df=j).......) , how do we > >> decide on the degree freedom to use for each smoother, and if we shold > >> apply smoother to each attribute? > >> > >> Thanks!! > >> > >> ______________________________________________ > >> [EMAIL PROTECTED] mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-help > >> PLEASE do read the posting guide! > >> http://www.R-project.org/posting-guide.html > >> > >> > > > > > > ----------------------------------------------------------------------- > > ----- > > -- > > Notice: This e-mail message, together with any > > attachments,...{{dropped}} > > > > ______________________________________________ > > [EMAIL PROTECTED] mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > > http://www.R-project.org/posting-guide.html > > > -- > Jari Oksanen, Oulu, Finland > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
