Displaying 20 results from an estimated 300 matches similar to: "partial mantel test"
2006 Oct 03
1
nlme_varcov matrix
Hi all!
Is there a function that provides the VarCov matrix
for a nlme objects? How I can extract the matrix for a
nlme model fitted?
I would appreciate any guidance
Regards
Lic. Gabriela Escati Pe?aloza
Biolog?a y Manejo de Recursos Acu?ticos
Centro Nacional Patag?nico(CENPAT).
CONICET
Bvd. Brown s/n?.
(U9120ACV)Pto. Madryn
Chubut
Argentina
Tel: 54-2965/451301/451024/451375/45401 (Int:277)
2006 Feb 02
1
Significance of degrees of freedom in nlme
Dear Dr. Bates,
Thank you very much for your response. I had consulted
the algorithm described in Pinheiro and Bates.
However, what I don't understand (among other things)
is why my two parameters appear to be estimated at
different grouping levels (based on the DF values).
Affect this different values of DF at the estimates
parameters? The estimates fixed effects were get at
the same level of
2006 Jan 27
1
how calculation degrees freedom
Hi, I' m having a hard time understanding the computation of degrees of freedom when runing nlme() on the following model:
> formula(my data.gd)
dLt ~ Lt | ID
TasavB<- function(Lt, Linf, K) (K*(Linf-Lt))
my model.nlme <- nlme (dLt ~ TasavB(Lt, Linf, K),
data = my data.gd,
fixed = list(Linf ~ 1, K ~ 1),
start = list(fixed = c(70, 0.4)),
na.action= na.include,
2006 May 24
1
problem-nlme
Hi,
I have great problems with my work in R.
I look for to model the growth of fish.
I have "Longitudinal data", a serie of repeated
measures for each individual.
Using the corresponding packages "nlme" in R.
I treat to fit to the data different growth functions,
wich were entered by me.
Unfortunately for no it was arrived at the
convergence, several error messages appeared.
I
2006 Jan 26
0
degrees freedom in nlme
I'm having hard time understanding the computation of degrees of freedom when runing nlme () on the following model:
> formula(my data.gd)
dLt ~ Lt | ID
TasavB<- function(Lt, Linf, K) (K*(Linf-Lt))
my model.nlme <- nlme (dLt ~ TasavB(Lt, Linf, K),
data = my data.gd,
fixed = list(Linf ~ 1, K ~ 1),
start = list(fixed = c(70, 0.4)),
na.action= na.include,
2009 Aug 05
1
stepwise
Dear R members,
I would like to know if there is a stepwise function that gives LRT value
instaed of AIC?
thanks in advance,
Luciana Pozzi
CENPAT-CONICET
Argentina
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2011 Apr 01
0
Using Restore
Hello:
I'm developing a fault tolerance system, and I'm trying to use save/restore
operation.
But it's working fine when I restore the file saved on the same guest, but
If I move it to another host, and then try to restore using the file
previously saved I got this error.
I ask for help to know if this kind of operation is allows, and if it is,
how can I do to work it.
The exactly
2009 Dec 17
2
mantel test and NAs
Dear R users,
I am having a problem performing the mantel test (both with functions mantel
{vegan} and mantel.test {ape}) due to I believe the presence of NAs on my
distance matrices, which look like e.g.:
NA
1 2
1 2 3
NA 4 5 6
and
1
1 2
2 3 4
5 6 7 8
Would any of you have a solution for that?
Thank you for much for your help!
Marcia Rocha
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2009 Sep 01
2
Mantel test least square line
Hello, I performed a Mantel test and plotted communitiy similarities. I
would like to add a least square line. I thought about using abline taking
as slope the r-statistic of the Mantel test and calculating the y-intercept
analytically. Is this method correct? Is there any function for this
calculation? Thank you
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2017 Dec 31
1
Perform mantel test on subset of distance matrix
I'm trying to perform a mantel test that ignores specific pairs in my
distance matrices. The reasoning is that some geographic distances
below a certain threshold suffer from spatial autocorrelation, or
perhaps ecological relationships become less relevant that stochastic
processes above a certain threshold.
The problem is that I can't find a way to do it. If I replace values
in either or
2009 Sep 14
1
Mantel test
Hello! It is not really linked to R, but can somebody explain me why we
sometimes make a mantel test directly for to distance matrices and sometimes
we first make a gradient analysis and then a mantel test between the axis?
Thank you
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2007 May 08
3
Mantel-Haenszel relative risk with Greenland-Robins variance estimate
Does anyone know of an R function for computing the Greenland-Robins
variance for Mantel-Haenszel relative risks?
Thanks
Frank
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
2008 Apr 19
1
Mantel-Haenszel for 2x2
Hi all,
Does anyone know if an R function for the Mantel-Haenszel chi-square for a
2x2 table exists? I’ve also seen it called the randomization Q statistic.
Note that I’m not looking for the Cochran-Mantel-Haenszel…I did see that out
there as cmh.test.
Thanks in advance,
Jeff
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2006 Oct 13
1
Mantel test!
Dear Sir/ Madam,
I would like to ask you about mantel test in R. In ade4 package, if I
want to use mantel.rtest, I get error massage "Object of class to "dist"
expected". As I already have two dissimilarity matrices, shall I again
compute distance measure using this function?
If not, could you please let me know which function/command I can use to
do?
Thank you very much in
2010 Jan 07
1
Mantel results shown in a graphical (histogram) form.
I am new at 'R' and not even sure whether I am contacting the appropriate
forum!! However, I have carried out several mantel tests (using 'R') on
genetic data and would like to plot the results in the form of a histogam of
the distribution - and preferably use a procedure that shows the critical
'r' value.
The tail end of my analysis is shown below. I just need help to dig
2011 May 31
0
Mantel - like analysis
Hello,
I've used mantel tests a fair bit for standard genetic/geographic/landscape
analyses. I realize it involves permutations of rows and columns in the
matrix to obtain correlation coefficients.
However, for a certain question, I am interested in populations that are
nearest neighbours to each other, and identifying factors that affect
genetic distance between them. So because of
2013 Mar 18
1
Mantel test for comparing two matrices
Hi everyone,
I have two matrices of 2000x2000 size. They consist of a measurement of
RMSD deviations of a protein structure. The basic question i want
to answer is the following: are there a significant differences between
the two matrices?
I aim to use the Mantel test. I don't really know if this is a good idea or
if there are better solutions for these mega matrices.
Thanks
[[alternative
2009 Mar 03
1
Mantel test!
Dear Gavin,
What is the interpretation of a simulated p-value of 1 in a mantel
test and how is the p-value derived? When we run two highly
negatively correlated matrices we get this result: r: -1, simulated p
value: 1
I would expect the high p-value of 1 to mean not significant. Could
you clarify?
Thank you,
Jason
Jason P. Sexton
Graduate Group in Ecology
University of California,
2011 Dec 03
1
partial mantel tests in ecodist with intential NA values.
I would like to perform partial mantel tests on only within group values, with "between group" values assigned to NA.
This is possible in package ncf partial.mantel.test, however this sues a different permutation to that used in ecodist.ecodist will not accept data with NA values, returning a "matrix is not square error.
is it possible to perform this test in ecodist?
many thanks
2009 Feb 27
1
Ordinal Mantel-Haenszel type inference
Hello,
I am searching for an R-Package that does an exentsion of the Mantel-Haenszel test for ordinal data as described in Liu and Agresti (1996) "A Mantel-Haenszel type inference for cummulative odds ratios". in Biometrics. I see packages such as Epi that perform it for binary data and derives a varaince for it using the Robbins and Breslow variance method. As well as another pacakge