Displaying 20 results from an estimated 1000 matches similar to: "var-covar matrices comparison"
2006 Feb 20
1
var-covar matrices comparison:
Hi,
Using package gclus in R, I have created some graphs that show the
trends within subgroups of data and correlations among 9 variables (v1-v9).
Being interested for more details on these data I have produced also the
var-covar matrices.
Question: From a pair of two subsets of data (with 9 variables each, I
have two var-covar matrices for each subgroup, that differ for a
treatment on one
2005 Jul 11
4
exact values for p-values
Hi there,
If I do an lm, I get p-vlues as
p-value: < 2.2e-16
Suppose am interested in exact value such as
p-value = 1.6e-16 (note = and not <)
How do I go about it?
stephen
2011 May 11
3
Vermunt's LEM in R
I don't know of any R package that can match all the functionality of LEM
eg fitting equality constraints to model parameters a la LISREL.
WRT dumping tables, I would have thought that as.data.frame.table does
pretty much what you want, [not tested]
newtab <- as.data.frame(table(a,b,c))
cat("dim\n")
for(i in seq(1, ncol(newtab)-1) {
cat(nlevels(newtab[,1]," ")
}
2013 Oct 09
1
Version of L-BFGS-B used in optim etc
Hi.
I just noticed the paper by Morales and Nocedal
Remark on "Algorithm 778: L-BFGS-B: Fortran Subroutines for Large-Scale
Bound Constrained Optimization". TOMS 2011; 38(1): 7
http://www.ece.northwestern.edu/~morales/PSfiles/acm-remark.pdf
which describes a couple of improvements (speed and accuracy) to the
original Netlib code which AFAICT is that still used by optim()
via f2c.
2005 Sep 27
1
Simulate phi-coefficient (correlation between dichotomous vars)
Newsgroup members,
I appreciate the help on this topic.
David Duffy provided a solution (below) that was quite helpful, and came
close to what I needed. It did a great job creating two vectors of
dichotomous variables with a known correlation (what I referred to as a
phi-coefficient).
My situation is a bit more complicated and I'm not sure it is easily
solved. The problem is that I must
2004 Dec 09
1
Re: Tetrachoric and polychoric correlations, Polycor package
A bit late, but you might like to look at
http://www.qimr.edu.au/davidD/polyr.R
Regarding the original posters queries:
You can analyse polychoric correlations as if they were Pearson
correlations using standard software (eg sem), and this usually doesn't do
too badly, or go to AWLS (Browne) in LISREL etc, or ML analysis
of the full multidimensional contingency table using programs such as
2005 Jun 29
2
How to convert "c:\a\b" to "c:/a/b"
I couldn't resist adding a more literal answer
unback <- function(x) {
chars <- unlist(strsplit(deparse(x),""))
chars <- chars[-c(1,length(chars))]
paste(gsub("\\\\","/",chars),collapse="")
}
unback("\n")
| David Duffy (MBBS PhD) ,-_|\
| email: davidD at qimr.edu.au ph:
2005 Jun 29
2
How to convert "c:\a\b" to "c:/a/b"
I couldn't resist adding a more literal answer
unback <- function(x) {
chars <- unlist(strsplit(deparse(x),""))
chars <- chars[-c(1,length(chars))]
paste(gsub("\\\\","/",chars),collapse="")
}
unback("\n")
| David Duffy (MBBS PhD) ,-_|\
| email: davidD at qimr.edu.au ph:
2007 Feb 05
3
RSNPper SNPinfo and making it handle a vector
If I run an analysis which generates statistical tests on many SNPs I would
naturally want to get more details on the most significant SNPs. Directly
from within R one can get the information by loading RSNPer (from
Bioconductor) and simply issuing a command SNPinfo(2073285). Unfortunately,
the command cannot handle a vector and therefore only wants to do one at a
time.
I tried the lapply and
2008 May 21
1
table(factor(x), exclude=NULL) (PR#11494)
Hi. I don't know if this a bug or just annoying to me:
> x <- c(1,2,3,NA)
> table(x, exclude=NULL)
x
1 2 3 <NA>
1 1 1 1
> table(factor(x), exclude=NULL)
1 2 3
1 1 1
I don't think many people use factor(x, exclude=NULL): it is not the
default handling of character data by read.table().
Cheers, David Duffy.
--
| David Duffy (MBBS PhD)
2007 Mar 07
3
Plotting a broken line?
Hi,
Is there a smart way in the R graphs to create a line that is broken in
intervals based on the indicator given below.
following is a small test graph
Location,indicator,otherinfo
1.2,1,2.2
2.5,1,2.5
3.7,1,2.3
20.1,2,4.3
22.5,2,5.2
25.0,2,3.4
27.3,2,2.2
35.1,3,3.4
37.0,3,7.2
38.0,3,6.1
40.1,3,5.4
52.9,3,3.3
Right now in the plot the line is continuous, but I would like to have
it broken
2007 Apr 26
2
Can a hyperlink be placed, thorugh R programming, on a graph?
Hi,
If I use
x<-1:10
y<-rnorm(10,0,1)
### pdf(file="c:\\aldi\\test.pdf")
plot(x,y)
segments(x,y,x+2,y+2)
segments(x,y,x+0.5,y+0.5,col=3)
### dev.off()
### q()
Is there a way that I can imbed in the graph plot for each point defined
by x to x+0.5 and y to y+0.5 (and colored in green) a different hyperlink?
For example point one (together with the green tail) will have the
2007 Nov 27
1
Packages for Animal Models & QG analyses
Hi,
I am looking to do some quantitative genetic analyses using animal models
and was wondering if someone could suggest an appropriate package in R. It
would help if it was similar to the ASReml genetic analyses software.
Thanks,
Deepa Senapathi
Deepa Senapathi
Centre for Agri-Environmental Research (CAER)
School of Agriculture, Policy & Developement.
University of Reading
2006 May 30
1
sib TDT transmission/disequilibrium test
Does anyone know if the sib TDT has been implemented in R
1. Spielman, R.S., and Ewens, W.J. (1998) A sibship test for linkage in the
presence of association: the sib transmission/disequilibrium test. Am J Hum
Genet 62, 450-458
--
Farrel Buchinsky, MD
Pediatric Otolaryngologist
Allegheny General Hospital
Pittsburgh, PA
2011 Feb 16
1
using the bootstrap method for latent class analysis
Hi
I was wondering whether anyone can provide any help or suggestions on the
boostrap method for latent class analysis please.
My main question is: can the bootstrap procedure sometimes be less precise
than the non-bootstrap procedure when carrying out latent class analysis?
I am asking this question because I carried out some analyses and when I *did
not* use the bootstrap procedure I found
2004 Oct 10
1
How to install a package that needs to see oher pkg dependencies:
Hi,
I am trying to install the genetics package on a server with Linux,
Fedora. I installed it in a PC and worked fine.
In a server since I am not used with R, I am not sure what do I need to
change so genetics pkg can see some package dependencies:
Any suggestion is appreciated, Aldi
Note:
genetics expects gregmisc and mvtnorm to be installed already. gregmisc
creates gdata etc dependencies.
2005 Aug 04
1
linkage disequilibrium
Dear all,
I'm using the package "Genetics", and I'm interested in the computation of D'
statistics for Linkage Disequilibrium, for which the LD() command has been
realised. Unfortunately I don't find any reference on "how" the D' is computed
by the LD() function. In the package documentation it is generally referred as
"MLE" estimation, but
2009 Mar 25
2
"with" and "by" and NA:
Hi,
I have a data.frame with many variables for which I am performing the
mean by subgroup, for a pair of variables at a time, where one of them
for each pair defines the subgroup. The subgroups in the x$cm1 are 0, 1
and 2.
x
ph1 cm1
0.2345 2
1.2222 1
2.0033 0
0.0000 2
1.0033 1
0.2345 0
1.2222 2
2.0033 0
0.0000 1
1.0033 2
> meanbygroup <- as.vector(with(x, by(x$ph1, x$cm1, mean)))
2006 Nov 26
2
Fixed zeros in tables
Hello All R Users,
Function loglm() in library MASS can be cajoled to accomodate
structural zeros in a cross-classification table. An example from
Fienberg demonstrates how this can be done.
My question is: Can the function glm() perform the same task? Can
glm() estimate a log-linear model with fixed zeros like loglm()?
Thanks for your help,
Andrew
## Fienberg, The Analysis of Cross-Classified
2007 Jun 27
3
exaustive subgrouping or combination
Dear Colleagues,
I am looking for a package or previous implemented R to subgroup and
exaustively divide a vector of squence into 2 groups.
For example:
1, 2, 3, 4
I want to have a group of
1, (2,3,4)
(1,2), (3,4)
(1,3), (2,4)
(1,4), (2,3)
(1,2,3), 4
(2,3), (1,4)
...
Can someone help me as how to implement this? I get some imaginary problem
when the sequence becomes large.
Thanks much in