Displaying 20 results from an estimated 7000 matches similar to: "Confidence ellipse for correlation"
2003 Oct 30
2
'nls' and its arguments
Dear R experts!
I'd to fit data by 'nls' with me-supplied function 'fcn'.
1) I'd like 'fcn' to accept arbitrary arguments, i.e. I defined it
as f(...) {<body>}. (Ok, that's not actually impotant).
2) Second, I would NOT like to supply every parameter in the formula.
To illustrate this, let's look at the last example of 'nls' help
2009 Nov 17
1
Define lm/glm object without evaluating them
For e.g. lm/glm type models I would like to separate model specification and model fitting and then only fit the models later 'when data arrives'. To be specific, I would like make a specification like
m1 <- lm(rate~conc)
m2 <- lm(rate~I(conc^2))
and then later I want to 'put data into' the objects and evaluate (fit the model), e.g. something like
update(m1, data=Puromycin)
2011 Apr 20
1
How can I 'predict' from an nls model with a fit specified for separate groups?
Following an example on p 111 in 'Nonlinear Regression with R' by Ritz &
Streibig, I have been fitting nls models using square brackets with the
grouping variable inside. In their book is this example, in which
'state' is a factor indicating whether a treatment has been used or not:
> Puromycin.m1 <- nls(rate ~ Vm[state] *
+ conc/(K[state] + conc), data = Puromycin,
2006 Nov 29
3
R2.4 xyplot + panel.number problem
Hi all;
I'm trying to display a 2 panel plot for the Puromycin data from R
with 2 different non-linear models fitted to each group. The problem
is that as far as I know panel.number doesn't work in the latest
version of R. Can anyone give a hint how to solve this?
Here is the code that I used before and now doesn't work
xyplot(rate ~conc| state,Puromycin,
2004 May 21
1
Buglet/omission in nls package (PR#6901)
Dear all,
I noticed the following under R 1.8.1 (when nls was still a separate
package) but the same problem occurs under R 1.9.0 (where most (all?)
of nls is now in the stats package):
> data(Puromycin)
> fm <- nls(rate~SSmicmen(conc,b0,b1), Puromycin, subset = state=="treated")
> coef(summary(fm))
NULL
The problem seems to be that summary.nls uses the name
2011 May 28
2
Observation in a confidence ellipse
Hello everyone
I really need some help here. I made a confidence ellipse using the function ellipse from the package ellipse:
ellipse(SD, centre=colMeans(pcsref),t=sqrt((p * (n-1)/(n-p))*qf(0.99, p,n-p))
Now, I want to write a function whom return TRUE or FALSE if a given observation is in the confidence ellipse. But I have no clue how to do it
Can anyone help me?
Best regards
Jessica
2005 Jun 15
1
ellipse -confidence interval
Hi!, I made a plot with two variables representing the first two axis of a
principle component analysis. My question is:
How can I superimpose on such plot an ellipse that represent the 95% interval of
confidence of scores?
Best regards,
Paula
--
Lic. Paula Gonzalez
Divisi??n Antropolog??a
Museo de La Plata.
Facultad de Ciencias Naturales y Museo. UNLP.
Paseo del Bosque s/n?? - B1900FWA - La
2004 Feb 02
1
Robust nonlinear regression - sin(x)/x?
You reall have only one parameter in your model, c = a/b. You can't
identify both a and b from your model, therefore, you should fit the
linear model: lm(z ~ c* sin(x)/x)
Ravi.
----- Original Message -----
From: cstrato <cstrato at aon.at>
Date: Monday, February 2, 2004 2:28 pm
Subject: [R] Robust nonlinear regression - sin(x)/x?
> Dear all
>
> Since I did not receive any
2013 Jan 26
2
confidence / prediction ellipse
Hi,
I'm using the R library(car) to draw confidence/prediction ellipses in a
scatterplot.
>From what i understood the ellipse() function return an ellipse based
parameters: shape, center, radius .
If i read dataEllipse() function i can see how these parameters are
calculated for a confidence ellipse.
ibrary(car)
a=c(12,12,4,5,63,63,23)
b=c(13,15,7,10,73,83,43)
v <-
2011 Aug 11
1
Splitting data
I want to implement the following algorithm in R:
I want to split my data, use a t test to compare both means of the groups to see if they significantly differ from each other. If this is a yes (p < alpha) I want to split again (into 4 groups) and do the same procedure twice, and stop otherwise (here the problem arises). As a final result I would have different groups of data.
I made some
2003 Feb 26
5
[Package car/data.ellipse]: confidence intervals off by factor sqrt(2)??? (PR#2584)
Full_Name: Volker Franz
Version: Version 1.6.2 (2003-01-10)
OS: Debian
Submission from: (NULL) (192.124.28.104)
Hi there,
it seems to me that data.ellipse of package "car" (Version 1.0-1)
produces confidence interval's which are too big. To see this, do:
library(car)
plot(c(-2,2),c(-2,2),pch=0)
data.ellipse(rnorm(10000),rnorm(10000),levels=0.68,plot.points=F)
abline(v=+1)
2007 Oct 16
1
simulation
I am trying to write a function that will simulate observed counts X and
Y as below, I want the function to be able give many replicates, can
somebody advise?
thanks
Oarabile
#alpha,n sdx and sdy are constant, and N is a vector of length n.
unstructured<-function(n,N,alpha,sdx,sdy){
Vx<-rnorm(n,mean=0,sd=sdx)
Vy<-rnorm(n,mean=0,sd=sdy)
thetax<-exp(alpha+Vx)
thetay<-exp(alpha+Vy)
2012 Feb 07
2
3D confidence ellipsoid with ellipse projections onto 2D plane
I have a 3xN matrix of parameters obtained from N regressions where the 3
parameters are jointly statistically significant. I would like to reproduce
a 3D confidence ellipsoid projecting 2D ellipses onto the XY plane as in
Figure 5.2 in this
2006 Nov 20
4
for help about logistic regression model
I have a dataset like this:
p aa
index x y z sdx sdy sdz delta as
ms cur sc
1 821p MET 1 -5.09688 32.8830 -5.857620 1.478200 1.73998 0.825778
13.7883 126.91 92.37 -0.1320180 111.0990
2 821p THR 2 -4.07357 28.6881 -4.838430 0.597674 1.37860 1.165780
13.7207 64.09 50.72 -0.0977129 98.5319
3 821p GLU 3 -5.86733 30.4759
2011 Jun 06
2
adding an ellipse to a PCA plot
Hi,
I created a principal component plot using the first two principal
components. I used the function princomp() to calculate the scores.
now, I would like to superimpose an ellipse representing the center
and the 95% confidence interval of a series of points in my plot (as
to illustrate the grouping of my samples).
I looked at the ellipse() function in the ellipse package but can't
get it
2008 Nov 03
2
standard errors for predict.nls?
Dear all,
Is there a way to retrieve standard errors from nls models? The help page tells me that arguments
such as se.fit are ignored...
Many thanks and 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 (0)551 39 8806
Homepage http://www.gwdg.de/~cscherb1
2008 Nov 14
1
Superimposing y-variables in Lattice formulas
Given a data frame of a categorical variable and two continuous
variables, I would like to display one continuous variable against the
other for each value of the categorical variable, all superimposed on
the same plot. For example:
data(Indometh); str(Indometh)
Classes 'nfnGroupedData', 'nfGroupedData', 'groupedData' and
'data.frame': 66 obs. of 3
2005 Jul 11
2
Weighted nls
Dear R Community,
I am attempting to perform a weighted non-linear least squares fit. It has already been noted that the weights option is not yet implemented for the nls function, but no one seems to offer any suggestions for getting around this problem. I am still curious if a) anyone has code they have written which includes a weight options for nls, or b) if there is another model which
2013 Sep 15
1
DataEllipse versus Ellipse Function in R
Hi:
Does Ellipse and dataellipse function in R produce the same ellipse? I
wanted to see how the radius for the Ellipse function in R calculated. Also
what is the var-covariance matrix, if any, assumed for the dataellipse
function? Heres an example of the code where I am generating Multivariate
normal data and creating ellipse using the 2 functions:
library(car)
library(mvtnorm)
mu =
2009 Apr 08
1
Is a point into an ellipse
Hi,
I drew an ellipse with the package ellipse. Now I would like to know if
a point is inside the ellipse. Is any R functions to do it without
computing the equation of the ellipse manually? Thanks.
For example, if I do "plot(ellipse(0.8), type = 'l')", I would like to
know if (0,1) belongs to the drawn ellipse.
Regards,
Alain
--
Alain Guillet
Statistician and Computer