Displaying 20 results from an estimated 500 matches similar to: "two basic question regarding model selection in GAM"
2004 Nov 01
2
Compilation error on mgcv_1.1-7 on OS X (10.3)
Greetings
I run into a compilation error when updating to mgcv_1.1-7 in R 2.0.0 on
OS X 10.3. Note that other pacakges have compiled nicely.
Some details are given below, but in short it looks like it's seeking for
/usr/local/lib/powerpc-apple-darwin6.8/3.4.2/
which I don't have. But I do have
/usr/lib/gcc/darwin/3.3
i.e a lower version of GCC in a different directory. More
2003 Sep 30
2
cluster & mgcv update
Hello,
After reinstalling the whole OS and R as well, I tried to update.packages()
and get the follwing error message:
concerning the mgcv update: atlas2-base is installed and blas as well (on
debian). I haven't found lf77blas, I assume it's a library or something
similar associated with blas.
any suggestion how to solve that, thanks Martin
* Installing *source* package
2008 Dec 09
1
update.packages() for R 2.7.1: mgcv fails
Hi
I just upgraded my debian/stable to R 2.7.1 via apt-get install r-base
r-base-core r-base-dev, and then
began to update.packages()
> update.packages(lib.loc="/usr/local/lib/R/site-library")
> update.packages(lib.loc="/usr/lib/R/library")
but I get:
....
* Installing *source* package 'mgcv' ...
** libs
gcc -std=gnu99 -I/usr/share/R/include -fpic -g
2003 Nov 25
1
Something broken with update?
Updating my 1.8.0 R installation (>update.packages() ) I obtain the following
(SORRY FOR THE LENGTH OF THE LOG BUT IT HELPS!!!):
................
downloaded 135Kb
KernSmooth :
Version 2.22-11 in /usr/lib/R/library
Version 2.22-12 on CRAN
Update (y/N)? y
mgcv :
Version 0.9-3.1 in /usr/lib/R/library
Version 0.9-6 on CRAN
Update (y/N)? y
trying URL
2012 Jul 24
1
questions on R CMD INSTALL et al
Greetings,
I am learning R
My machine has these;
CPU: 3cores amd64
OS pure-64bit CBLFS liux compiled from sources (kernel 3.2.1, gcc-4.6.2
R-2.15
When I compiled R the compiler spewed out lines like these:-
make[3]: Entering directory `/tmp/RtmpiHdDJy/R.INSTALL472339eeb23a/mgcv/src'
gcc -m64 -std=gnu99 -I/home/Rman/R-2.15.0/include -DNDEBUG -
I/usr/local/atlas/include
2004 Mar 12
1
GCV UBRE score in GAM models
hello to everybody:
I would to know with ranges of GCV or UBRE values can be considered as
adequate to consider a GAM as correct
Thanks in advance
--
David Nogu?s Bravo
Functional Ecology and Biodiversity Department
Pyrenean Institute of Ecology
Spanish Research Council
Av. Monta?ana 1005
Zaragoza - CP 50059
976716030 - 976716019 (fax)
2012 Feb 13
3
mgcv: increasing basis dimension
hi
Using a ts or tprs basis, I expected gcv to decrease when increasing the
basis dimension, as I thought this would minimise gcv over a larger
subspace. But gcv increased. Here's an example. thanks for any comments.
greg
#simulate some data
set.seed(0)
x1<-runif(500)
x2<-rnorm(500)
x3<-rpois(500,3)
d<-runif(500)
linp<--1+x1+0.5*x2+0.3*exp(-2*d)*sin(10*d)*x3
2007 Jun 21
1
mgcv: lowest estimated degrees of freedom
Dear list,
I do apologize if these are basic questions. I am fitting some GAM
models using the mgcv package and following the model selection criteria
proposed by Wood and Augustin (2002, Ecol. Model. 157, p. 157-177). One
criterion to decide if a term should be dropped from a model is if the
estimated degrees of freedom (EDF) for the term are close to their lower
limit.
What would be the
2009 Jul 07
3
Error due to non-conformable arrays
Hello,
Consider this function for generalized ridge regression:
gre <- function (X,y,D){
n <- dim(X)[1]
p <- dim(X)[2]
intercept <- rep(1, n)
X <- cbind(intercept, X)
X2D <- crossprod(X,X)+ D
Xy <- crossprod(X,y)
bth <- qr.solve(X2D, Xy)
}
# suppose X is an (nxp) design matrix and y is an (nx1) response vector
p <- dim(x)[2]
D<- diag(rep(1.5,p))
bt
2002 Sep 10
2
Hat values for generalized additive models
Would anyone be able to provide insight for the following question, please?
Setting: estimation of prediction intervals for age-period-cohort models
using GAMs (rate ~ s(age,period))
Method: bootstrap (Davison and Hinkley, 1997)
Issue: standardisation of the residuals for resampling requires an
adjustment using the diagonals of the hat matrix.
Is there a simple way to get the hat values out of a
2003 Jun 04
2
gam()
Dear all,
I've now spent a couple of days trying to learn R and, in particular, the
gam() function, and I now have a few questions and reflections regarding
the latter. Maybe these things are implemented in some way that I'm not yet
aware of or have perhaps been decided by the R community to not be what's
wanted. Of course, my lack of complete theoretical understanding of what
2008 Aug 20
5
GAM-binomial logit link
Dear all,
I'm using a binomial distribution with a logit link function to fit a GAM model. I have 2 questions about it.
First i am not sure if i've chosen the most adequate distribution. I don't have presence/absence data (0/1) but I do have a rate which values vary between 0 and 1. This means the response variable is continuous even if within a limited interval. Should i use
2012 Jun 21
2
MGCV: Use of irls.reg option
Hi,
In the help files in the ?mgcv package for the gam.control() function,
there is an option irls.reg. The help files describe this option as:
For most models this should be 0. The iteratively re-weighted least squares
method by which GAMs are fitted can fail to converge in some circumstances.
For example, data with many zeroes can cause problems in a model with a log
link, because a mean of
2004 Jun 03
3
Problem with mgcv PACKAGES file format?
Hello All,
I'm getting this error (Version: 1.9.0-1 on a debian system)
> update.packages("mgcv")
trying URL `ftp://mirror.aarnet.edu.au/pub/cran/src/contrib/PACKAGES'
ftp data connection made, file length 169516 bytes
opened URL
.......... .......... .......... .......... ..........
.......... .......... .......... .......... ..........
.......... .......... ..........
2009 Mar 31
1
CV and GCV for finding smoothness parameter
I received an assignment that I have to do in R, but I'm absolutely not very
good at it.
The task is the following:
http://www.nabble.com/file/p22804957/question8.jpg
To do this, we also get the following pieces of code (not in correct order):
http://www.nabble.com/file/p22804957/hints.jpg
I'm terrible at this and I'm completely stuck. The model I chose can be
found in here:
2005 Sep 26
4
p-level in packages mgcv and gam
Hi,
I am fairly new to GAM and started using package mgcv. I like the
fact that optimal smoothing is automatically used (i.e. df are not
determined a priori but calculated by the gam procedure).
But the mgcv manual warns that p-level for the smooth can be
underestimated when df are estimated by the model. Most of the time
my p-levels are so small that even doubling them would not result
2002 Nov 13
2
Comparing GAM objects using ANOVA
Hi,
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
2004 Jan 19
2
Relative risk using GAM
I am a new user of R. I am trying to fit gam model with our air pollution data. I used Foreign package to call data from SPSS and used MGCV package to fit gam. The following are the steps I used:
> dust<- read.spss("a:dust9600jan.sav")
> c<-gam(MRESPALL~s(DUSTM)+s(TEMP)+s(RH),family=poisson,data=dust)
> summary(c)
Family: poisson
Link function: log
Formula:
MRESPALL ~
2006 Dec 04
1
GAM model selection and dropping terms based on GCV
Hello,
I have a question regarding model selection and dropping of terms for GAMs fitted with package mgcv. I am following the approach suggested in Wood (2001), Wood and Augustin (2002).
I fitted a saturated model, and I find from the plots that for two of the covariates,
1. The confidence interval includes 0 almost everywhere
2. The degrees of freedom are NOT close to 1
3. The partial
2008 Mar 31
1
unexpected GAM result - at least for me!
Hi
I am afraid i am not understanding something very fundamental.... and does not matter how much i am looking into the book "Generalized Additive Models" of S. Wood i still don't understand my result.
I am trying to model presence / absence (presence = 1, absence = 0) of a species using some lidar metrics (i have 4 of these). I am using different models and such .... and when i