Displaying 20 results from an estimated 3000 matches similar to: "How to specify a constant in gnls{nlme}"
2004 Nov 25
1
Error in anova(): objects must inherit from classes
Hello:
Let me rephrase my question to attract interest in the problem I'm having. When I appply anova() to two equations
estimated using glmmPQL, I get a complaint,
> anova(fm1, fm2)
Error in anova.lme(fm1, fm2) : Objects must inherit from classes "gls",
"gnls" "lm","lmList", "lme","nlme","nlsList", or "nls"
2004 Nov 26
1
help with glmmPQL
Hello:
Will someone PLEASE help me with this problem. This is the third time
I've posted it.
When I appply anova() to two equations estimated using glmmPQL, I get a
complaint,
> anova(fm1, fm2)
Error in anova.lme(fm1, fm2) : Objects must inherit from classes "gls",
"gnls" "lm","lmList", "lme","nlme","nlsList", or
1999 Nov 25
1
gnls
Doug,
I have been attempting to learn a little bit about nlme without too
much documentation except the online help. The Latex file in the nlme
directory looks interesting but uses packages that I do not have so
that I have not been able to read it.
I have run the example from gnls to compare it with the results I
get from my libraries (code below - I have not included output as it
is rather
2009 Jan 07
1
Extracting degrees of freedom from a gnls object
Dear all,
How can I extract the total and residual d.f. from a gnls object?
I have tried str(summary(gnls.model)) and str(gnls.model) as well as gnls(), but couldn?t find the
entry in the resulting lists.
Many thanks!
Best wishes
Christoph
--
Dr. rer.nat. Christoph Scherber
University of Goettingen
DNPW, Agroecology
Waldweg 26
D-37073 Goettingen
Germany
phone +49 (0)551 39 8807
fax +49
2002 Oct 04
1
gnls from library nlme
Dear all,
I am trying to gain some experience with the function gnls from the nlme
package.
I tried to model the Theophyline data by trying to model the presumed
dependency of
the clearance on the body weight.
This is my function call of gnls:
gnls(conc~SSfol(Dose,Time,lKe,lKa,lCl),data=Theoph,
params=list(lKe~1,lKa~1,lCl~Wt),start=c(-2.4,0.46,-3.22,0.01))
That's been the result:
Error
2008 Sep 27
1
seg.fault from nlme::gnls() {was "[R-sig-ME] GNLS Crash"}
>>>>> "VW" == Viechtbauer Wolfgang (STAT) <Wolfgang.Viechtbauer at STAT.unimaas.nl>
>>>>> on Fri, 26 Sep 2008 18:00:19 +0200 writes:
VW> Hi all, I'm trying to fit a marginal (longitudinal)
VW> model with an exponential serial correlation function to
VW> the Orange tree data set. However, R crashes frequently
VW>
2004 Oct 01
4
gnls or nlme : how to obtain confidence intervals of fitted values
Hi
I use gnls to fit non linear models of the form y = alpha * x**beta
(alpha and beta being linear functions of a 2nd regressor z i.e.
alpha=a1+a2*z and beta=b1+b2*z) with variance function
varPower(fitted(.)) which sounds correct for the data set I use.
My purpose is to use the fitted models for predictions with other sets
of regressors x, z than those used in fitting. I therefore need to
2005 Jul 26
1
evaluating variance functions in nlme
Hi,
I guess this is a final plea, and maybe this should go to R-help but
here goes.
I am writing a set of functions for calibration and prediction, and to
calculate standard
errors and intervals I need the variance function to be evaluated at new
prediction points.
So for instance
fit<-gnls(Y~SSlogis(foo,Asym,xmid,scal),weights=varPower())
2005 Nov 17
1
anova.gls from nlme on multiple arguments within a function fails
Dear All --
I am trying to use within a little table producing code an anova
comparison of two gls fitted objects, contained in a list of such
object, obtained using nlme function gls.
The anova procedure fails to locate the second of the objects.
The following code, borrowed from the help page of anova.gls,
exemplifies:
--------------- start example code ---------------
library(nlme)
##
2009 Jun 24
1
gnls : Rho
Hello list:
How to extract the value of "Rho" from a gnls() object. I am using gnls()
function similar to
res <- gnls(y~SSmicmen(),correlation=corCompSymm(form~1|b),data=dat)
Thanks in advance,
Mahbub.
--
Mahbub Latif
School of Mathematical Sciences
Queen Mary, University of London
United Kingdom
[[alternative HTML version deleted]]
2001 Jun 01
1
nls works but not gnls
This works fine:
fit42<-nls(Vfs~SSlogis(Months,Asym.Int+Asym.Group*Groupdum,xmid,scal),
data=df,
start=c(Asym.Int=22,Asym.Group=5,xmid=2,scal=6),
na.action=na.omit)
But this, identical except using gnls, doesn't converge:
fit43<-gnls(Vfs~SSlogis(Months,Asym.Int+Asym.Group*Groupdum,xmid,scal),
data=df,
start=c(Asym.Int=22,Asym.Group=5,xmid=2,scal=6),
na.action=na.omit)
Error in gnls(Vfs
2003 Aug 14
1
gnls - Step halving....
Hi all,
I'm working with a dataset from 10 treatments, each
treatment with 30 subjects, each subject measured 5
times. The plot of the dataset suggests that a
3-parameter logistic could be a reasonable function to
describe the data. When I try to fit the model using
gnls I got the message 'Step halving factor reduced
below minimum in NLS step'. I´m using as the initial
values of the
2005 Mar 02
1
Using varPower in gnls, an answer of sorts.
Back on January 16, a message on R-help from Ravi Varadhan described a
problem with gnls using weights=varPower(). The problem was that the
fit failed with error
Error in eval(expr, envir, enclos) : Object "." not found
I can reliably get this error in version 2.0.1-patched 2004-12-09 on
Windows XP and 2.0.1-Patched 2005-01-26 on Linux.
The key feature of that example is that the
2008 Sep 02
1
Non-constant variance and non-Gaussian errors with gnls
I have been using the nls function to fit some simple non-linear
regression models for properties of graphite bricks to historical
datasets. I have then been using these fits to obtain mean predictions
for the properties of the bricks a short time into the future. I have
also been calculating approximate prediction intervals.
The information I have suggests that the assumption of a normal
2003 Apr 19
1
nls, gnls, starting values, and covariance matrix
Dear R-Help,
I'm trying to fit a model of the following form using gnls. I've fitted it
using nlsList with the following syntax:
nlsList(Y~log(exp(a0-a1*X)+exp(b0-b1*X))|K,start=list
(a0=6,a1=0.2,b0=4.5,b1=0.001),data=data.frame(Y=y,X=X,K=k)))
which works just fine:
<snip>
Coefficients:
a0 a1 b0 b1
1 5.459381 0.5006811 5.137458 -0.0040548687
2003 Sep 16
2
gnls( ) question
Last week (Wed 9/10/2003, "regression questions") I posted
a question regarding the use of gnls( ) and its dissimilarity
to the syntax that nls( ) will accept. No one replied, so
I partly answered my own question by constructing indicator
variables for use in gnls( ). The code I used to construct
the indicators is at the end of this email.
I do have a nagging, unanswered
2004 Aug 27
2
degrees of freedom (lme4 and nlme)
Hi, I'm having some problems regarding the packages
lme4 and nlme, more specifically in the denominator
degrees of freedom. I used data Orthodont for the two
packages. The commands used are below.
require(nlme)
data(Orthodont)
fm1<-lme(distance~age+ Sex,
data=Orthodont,random=~1|Subject, method="REML")
anova(fm1)
numDF DenDF F-value p-value
(Intercept) 1
2007 Apr 26
1
gnls warning message
Dear R users;
I was trying to fit a nonlinear model using gnls (nlme version 3.1-80,
R 2.5.0, WinXP) and I got the following error and warning message:
Error in gnls(ht ~ a1 * hd * (1 - a2 * exp(-a3 * (dbh/dq2))), data = hdat, :
Step halving factor reduced below minimum in NLS step
In addition: Warning message:
$ operator is deprecated for atomic vectors, returning NULL in:
2001 Sep 07
3
fitting models with gnls
Dear R-list members,
Some months ago I wrote a message on the usage of gnls (nlme library) and here I come again.
Let me give an example:
I have a 10 year length-at-age data set of 10 fishes (see growth.dat at the end of this message) and I want to fit a von Bertalanffy growth model, Li= Linf*(1-exp(-k*(ti-t0))) where Li = length at age i, Linf= asymptotic length, k= curvature parameter, ti=
2004 Nov 25
0
MASS problem -- glmmPQL and anova
Hello:
I am really stuck on this problem. Why do I get an error message with
anova() when I compare these two equations?
Hope someone can help.
ANDREW
____________________________
> fm1 <- glmmPQL(choice ~ day + stereotypy,
+ random = ~ 1 | bear, data = learning, family = binomial)
> fm2 <- glmmPQL(choice ~ day + envir + stereotypy,
+ random = ~ 1 |