Displaying 20 results from an estimated 9000 matches similar to: "GAMs under R?"
2000 Apr 30
0
Help Need with aov()
Hi there,
I'm using R1.0.1 Windows 98.
This file contains some inputs and an aov function code. Can someone
check it for me? Somehow I got completely different answer when typing
them in R and in Splus.
Splus gives me this:
> summary( Turnip.aov )
Error: Blocks
Df Sum of Sq Mean Sq F Value Pr(F)
Residuals 3 163.7367 54.57891
Error: Plots %in% Blocks
2000 Oct 03
5
Where is gam?
I noticed that there is no generalised additive model functions in R
(1.1.1) ... is there a package that implements them?
Thanks
Prasad
*****************************************************************
Mr. Anantha Prasad, Ecologist/GIS Specialist
USDA Forest Service, 359 Main Rd.
Delaware OHIO 43015 USA
Ph: 740-368-0103 Email: aprasad at fs.fed.us
Web:
2004 Aug 06
2
gam --- a new contributed package
I have contributed a "gam" library to CRAN,
which implements "Generalized Additive Models".
This implementation follows closely the description in
the GAM chapter 7 of the "white" book "Statistical Models in S"
(Chambers & Hastie (eds), 1992, Wadsworth), as well as the philosophy
in "Generalized Additive Models" (Hastie & Tibshirani 1990,
2004 Aug 06
2
gam --- a new contributed package
I have contributed a "gam" library to CRAN,
which implements "Generalized Additive Models".
This implementation follows closely the description in
the GAM chapter 7 of the "white" book "Statistical Models in S"
(Chambers & Hastie (eds), 1992, Wadsworth), as well as the philosophy
in "Generalized Additive Models" (Hastie & Tibshirani 1990,
2007 Apr 09
1
Could not fit correct values in discriminant analysis by bruto.
Shuji,
I suspect that bruto blows up because your data are linearly separable.
To see this (if you didn't already know), try
library(lattice)
splom(~x, groups = y)
and look at the first row. If you are trying to do classification, there
are a few methods that would choke on this (logistic regression) and a
few that won't (trees, svms etc). I would guess that bruto is in the
latter
2002 Sep 15
7
loess crash
Hi,
I have a data frame with 6563 observations. I can run a regression with
loess using four explanatory variables. If I add a fifth, R crashes. There
are no missings in the data, and if I run a regression with any four of the
five explanatory variables, it works. Its only when I go from four to five
that it crashes.
This leads me to believe that it is not an obvious problem with the data,
2006 Jan 19
2
gam
Dear R users,
I'm new to both R and to this list and would like to get
advice on how to build generalized additive models in R.
Based on the description of gam, which I found on the R
website, I specified the following model:
model1<-gam(ST~s(MOWST1),family=binomial,data=strikes.S),
in which ST is my binary response variable and MOWST1 is a
categorical independent variable.
I get the
2010 Apr 06
1
GAMs and survival data
Hello. I'm trying to analyze data, which is looking at the relationship between temperature and survival for fish (from fertilization to emergence). Looking at the raw data, there appears to be a bell shaped relationship. Ordinarily for survival data, I would run a generalized linear model (because the data has a binomial error structure). However, I am thinking that running a generalized
2006 Oct 27
3
R & gams
At office I have been introduced by another company to new, complex energy
forecasting models using gams as the basic software.
I have been told by the company offering the models that gams is specialised
in dealing with huge, hevy-weight linear and non-linear modelling (see an
example in http://www.gams.com/modtype/index.htm) and they say it is almost
the only option for doing it.
I would
2007 Dec 13
1
Two repeated warnings when runing gam(mgcv) to analyze my dataset?
Dear all,
I run the GAMs (generalized additive models) in gam(mgcv) using the
following codes.
m.gam
<-gam(mark~s(x)+s(y)+s(lstday2004)+s(ndvi2004)+s(slope)+s(elevation)+disbinary,family=binomial(logit),data=point)
And two repeated warnings appeared.
Warnings$B!'(B
1: In gam.fit(G, family = G$family, control = control, gamma = gamma, ... :
Algorithm did not converge
2: In gam.fit(G,
2002 Jan 28
6
Almost a GAM?
Hello:
I sent this question the other day with the wrong subject
heading and couple typos, with no response. So,
here I go again, having made those corrections.
I would like to estimate, for lack of a better description,
a partially additive non-parametric model with the following
structure:
z~ f(x,y):w1 + g(x,y):w2 + e
In other words, I'd like to estimate the marginals with
respect to
2013 Nov 06
3
Nonnormal Residuals and GAMs
Greetings, My question is more algorithmic than prectical. What I am
trying to determine is, are the GAM algorithms used in the mgcv package
affected by nonnormally-distributed residuals?
As I understand the theory of linear models the Gauss-Markov theorem
guarantees that least-squares regression is optimal over all unbiased
estimators iff the data meet the conditions linearity,
2008 Feb 16
2
Possible overfitting of a GAM
The subject is a Generalized Additive Model. Experts caution us against
overfitting the data, which can cause inaccurate results. I am not a
statistician (my background is in Computer Science). Perhaps some kind soul
would take a look and vet the model for overfitting the data.
The study estimated the ebb and flow of traffic through a voting place. Just
one voting place was studied; the
2008 Sep 03
1
Non-constant variance and non-Gaussian errors
Hi Paul,
Take a look at gam() from package mgcv (gam = generalized additive models), maybe this will help you. GAMs can work with other distributions as well. Generalized additive models consist of a random component, an additive component, and a link function relating these two components. The response Y, the random component, is assumed to have a density in the exponential family. I am not sure
2007 Jun 22
1
two basic question regarding model selection in GAM
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
2008 Jan 03
1
GLM results different from GAM results without smoothing terms
Hi, I am fitting two models, a generalized linear model and a generalized
additive model, to the same data. The R-Help tells that "A generalized
additive model (GAM) is a generalized linear model (GLM) in which the linear
predictor is given by a user specified sum of smooth functions of the
covariates plus a conventional parametric component of the linear
predictor." I am fitting the GAM
2007 Apr 03
3
Testing additive nonparametric model
I have estimated a multiple nonparametric regression using the loess
command in R. I have also estimated an additive version of the model using
the gam function. Is there a way of using the output of these two models to
test the restrictions imposed by the additive model?
2000 Nov 03
3
QUERY: gam models in R?
Hi Allstaters,
Does anybody know if the R package can fit
Generalised Additive Models?.
Thanks indeed,
Aurelio.
atobias at ole.com
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2007 Apr 08
1
Relative GCV - poisson and negbin GAMs (mgcv)
I am using gam in mgcv (1.3-22) and trying to use gcv to help with model selection. However, I'm a little confused by the process of assessing GCV scores based on their magnitude (or on relative changes in magnitude).
Differences in GCV scores often seem "obvious" with my poisson gams but with negative binomial, the decision seems less clear.
My data represent a similar pattern as
2001 Aug 12
3
gam() and library( modreg )
Hi,
I'm just wonder if there is an R equivalent function of gam() - which
exist in Splus.
Also does anyone know if the library( modreg ), which comes with the
installation file of R 1.3.0 (Windows version), exists in the previous
versions of R (again, Windows version)? Or does one need to install the
library into the previous versions of R explicitly?
Thanks,
Ko-Kang Wang