Displaying 20 results from an estimated 93 matches for "mantel".
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mandel
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....
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!...
2006 May 19
4
Cross correlation/ bivariate/ mantel
...ude, fish larvae) at the same 280 stations (i.e. 280 cases). I want to determine if the 2 datasets are spatially correlated. In other words, do high numbers of larvae occur where there are high numbers of eggs? I would like to calculate the cross correlation for these bivariate data and calculate a Mantel statistic as described on pg. 147 of Fortin and Dale 2005 "Spatial analysis".
My search of R packages came up with acf and ccf functions but I don't think these are what I want. Does anyone know which spatial package I might find the appropriate test, please?
> Best fishes
>...
2010 Apr 04
2
"mantel.haenszel.test for trend in S-plus doesn't work i R"
Dear R'ers,
When I used S-plus i wrote a small program for a Mantel-Haenszel test
for trend (I think it worked). Unfortunately I can't get it working in
R.
It appears as if my use of 'el' is the problem but I can't sort it out.
Error in apply(array, c(, 2, 3), function(el) el * 1:s) :
argument is missing, with no default
Further down in the...
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
--
View thi...
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
--
View this message in context: http://www.nabble.com/Mantel-test-tp25439984p25439984.html
Sent from the R help mailing list archive at Nabble.com.
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...
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
2013 May 06
2
BIOENV
Dear all,
Does anyone knows why the results of a BIOENV (PRIMER v. 6.1.15) are
diferent of the bioenv() + mantel() in vegan? Not the spearman correlation,
indeed the pseudo-p value.
I know that the approach bioenv() + mantel() is biased. So, how the BIOENV
(PRIMER) ends with larger p values (permutated).
Acctualy how the permutation test in BIOENV (PRIMER) is conducted. The user
guide does not make it clear...
2012 Sep 18
1
Cochran-Mantel-Haenszel test
...t 200 51.6 2.0640000
31 wint night 300 411.4 16.4560000
32 wint night 500 1981.2 79.2480000
I wanted to test whether significant differences existed between depth
in summer vs. winter, and day vs. night, controlling first for season
and then for time of day. I carried out a Cochran-Mantel-Haenszel test,
using Average Frequency (Avrg) as the dependent variable (2x2x8
contingency table).
> ct<-xtabs(Avrg~Time+Depth+Season,data=HG03.dat)
> mantelhaen.test(ct)
Cochran-Mantel-Haenszel test
data: ct
Cochran-Mantel-Haenszel M^2 = 28.4548, df = 7, p-value = 0.0001818...
2001 Apr 28
2
Mantel's randomization test
Dear all,
Dose anyone know whether there is a good R packege or
program for Mantel's randomization test?
Thanks in advance.
------------------------
Takashi Mizuno
zoono at sci.osaka-cu.ac.jp
Plant Ecology Lab.
Osaka City University
------------------------
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2006 Feb 23
1
partial mantel test
I would like to know how to run a partial mantel test controlling for spatial
autocorrelation and correlation with other environmental variables. It seems that
with function included in vegan for partial mantel test I can only test for the
relationship between two variables controlling for the effect of a third one.
Thanks a lot
Alexandra
---...
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
Internal Virus Database is out-of-date.
Checked by AVG Free Edition....
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 out an
instruction to follow on...
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/comm...
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...
2012 Mar 14
2
Using the mantel test in Ape Package
Hi,
I am trying to use a mantel test on two distance matrices. The code I have entered for each is:
Gen_dists <- read.csv(file.choose(),
stringsAsFactors = FALSE,
na.strings = c(" "),...
2003 Sep 12
2
partial mantel
Dear all,
Has anyone written R code for partial Mantel Tests- as described for
instance in Legtendre & Legendre (1998) ?
In other words, in a community ecology analysis, I would like to calculate
the correlation between two dissimilarity matrices, controlling for a third
distance matrix representing geographical distances between sites.
Thanks!
C...
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
Univ...
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
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