Displaying 20 results from an estimated 10000 matches similar to: "Orders of levels affecting wilcox.test() output"
2013 Sep 16
3
b
Estimado José, por lo que estuve mirando aqui
https://en.wikipedia.org/wiki/Wilcoxon_signed-rank_test, en ?wilcox.test
y en libros de papel ... los datos deben cumplir ciertas condiciones,
quiza la mas restrictiva es que sean pareados ... si no lo son, quiza
esta variante del test es mas apropiada:
https://en.wikipedia.org/wiki/Mann-Whitney-Wilcoxon_test
la que en R se aplica usando el mismo
2010 Feb 24
1
extracting results from wilcox_test (package::coin)
Recently, I ran a series of Kruskal-Wallace tests [kruskal.test()] using by()
to group by site Output is a list:
>Herb.KW
Herb.df$ID: 10-1
Kruskal-Wallis rank sum test
data: Indicator_Rating by Year
Kruskal-Wallis chi-squared = 15.24, df = 7, p-value = 0.03302
-----------------------------------------------------------------------------------------------------
Herb.df$ID: 18-1
2011 Oct 31
2
one sample Wilcoxon test using 'coin'
Hi,
R allows me to run a one sample Wilcoxon test like this:
wilcox.test(c(1,3.5,2.1,4,1.5,5), mu=2, exact=TRUE)
The function 'wilcoxsign_test' from the package 'coin' should (I
suppose) be able to calculate exact p values even if there are ties in
the ranks. However, I couldn't find information on how to run a one
sample test using 'wilcoxsign_test' like in the
2010 Aug 20
2
U value from wilcox.test
Dear all,
I want to compare the efficiency of 2 methods in extracting proteins from
algal samples. I collected 6 independant algal samples and I extracted 3 by
the method 1 and 3 others by the method 2.
So I have 2 groups of 3 samples, that are not paired. I would like to know
if the results obtained by these 2 methods are significantly different, I
hope method 2 to be more efficient than method
2002 Oct 15
2
V-value in the wilcox.test resp. wilcox.exact
hi,
when performing a wilcox.test or a wilcox.exact i get results that looks
like this:
wilcox.exact(x, mu=.5)
Exact Wilcoxon signed rank test
data: x
V = 207, p-value = 0.0006905
alternative hypothesis: true mu is not equal to 0.5
the way i understand the wilcox.test (or wilcox.exact) the V-value
represents the summed up ranks of either the positive or negative
differences,
2005 Aug 17
1
trouble with wilcox.test
I'm having trouble with the wilcox.test command in R. To demonstrate the anomalous behavior of wilcox.test, consider
> wilcox.test(c(1.5,5.5), c(1:10000), exact = F)$p.value
[1] 0.01438390
> wilcox.test(c(1.5,5.5), c(1:10000), exact = T)$p.value
[1] 6.39808e-07 (this calculation takes noticeably longer).
> wilcox.test(c(1.5,5.5), c(1:20000), exact = T)$p.value
(R closes/crashes)
2003 Aug 06
1
wilcox.test, CI (PR#3666)
Full_Name: David Wooff
Version: 1.7.0
OS: i686-pc-linux-gnu
Submission from: (NULL) (129.234.4.10)
wilcox.test exits with error message when confidence interval required, under
some situations. I suspect this occurs when the data contain a zero and for some
data lengths only:
print(wilcox.test(c(2,1,4,3,6,-5,0),conf.int=T))
fails
print(wilcox.test(c(2,1,4,3,6,-5,0,1),conf.int=T))
works
2009 Nov 01
1
wilcox.test construction in r
Hi, I am very confused with constructing the wilcox.test in R.
I have two populations 'original' and 'test'.
I want to know if the 'test' is generally 'lower' than original.
I use alpha of 0.05.
So do I write the function as wilcox.test(original, test, alternative="l")?
or wlcox.test(original, test, alternative = "g")?
or wilcox.test(test,
2008 Oct 25
1
pairwise.wilcox.test for paired samples
Dear R Core,
pairwise.wilcox.test does not handle "paired = TRUE" correctly; e.g.
set.seed(13)
x <- rnorm(20)
g <- c(rep(1, 10), rep(2, 10))
wilcox.test(x ~ g)$p.value # 0.075
pairwise.wilcox.test(x, g)$p.value # 0.075, o.k
wilcox.test(x ~ g, paired = TRUE)$p.value # 0.105
pairwise.wilcox.test(x, g, paired = TRUE)$p.value # 0.075, wrong
The line
wilcox.test(xi, xj,
2011 Jun 14
4
BIZARRE results from wilcox.test()
I get these BIZARRE results from wilcox.test()
When INCREASING the number of samples i get INCREASED p-values. When
increasing the number of samples further, the p-values goes down again. This
seems really bizarre!
Can anyone explain why this is so?!
Example:
> w <- wilcox.test(c(1:40),(c(1:40)+100))
> w$p.value
[1] 1.860340e-23
> w <- wilcox.test(c(1:50),(c(1:50)+100))
>
2006 Oct 05
1
The W statistic in wilcox.exact
Does anyone know why wilcox.exact gives W-statistic 6 instead of 12 as indicated below.
12 is the rank sum of group 0 of x, which is the linear statistic computed by wilcox_test.
y<-c(1,2,3,4,5)
x<-c(1,1,0,0,0)
(a) wilcox.exact
wilcox.exact(y~x)
Exact Wilcoxon rank sum test
data: y by x
W = 6, p-value = 0.2
alternative hypothesis: true mu is not equal to 0
(b) wilcox_test
2019 Dec 07
5
Inconsistencies in wilcox.test
Hello,
Writing to share some things I've found about wilcox.test() that seem a
a bit inconsistent.
1. Inf values are not removed if paired=TRUE
# returns different results (Inf is removed):
wilcox.test(c(1,2,3,4), c(0,9,8,7))
wilcox.test(c(1,2,3,4), c(0,9,8,Inf))
# returns the same result (Inf is left as value with highest rank):
wilcox.test(c(1,2,3,4), c(0,9,8,7), paired=TRUE)
2006 Nov 08
2
interprete wilcox.test results
Dear All,
I am using wilcox.test to test two samples, data_a and data_b, earch sample has 3 replicates, suppose data_a and data_b are 20*3 matrix. Then I used the following to test the null hypothesis (they are from same distribution.):
wilcox.test(x=data_a, y=data_b, alternative="g")
I got pvalue = 1.90806170863311e-09.
When I switched data_a and data_b by doing the following:
2006 Sep 07
1
Running wilcox.test function on two lists
Dear all,
I'm a newbie to R and I would really apperciate any help with the following:
I have two lists, l1 and l2:
l1:
$"A*0101"
[1] 0.076 0.109 0.155 0.077 0.09 0 0 0.073
[9] 0.33 0.0034 0.0053
$"A*0247"
[1] 0 0 0.5 .004 0 0 0
$"A*0248"
[1] 0 0 0.3 0 0.06
....
l2:
$"A*1101"
[1] 0.17 0.24 0.097 0.075 0.067
$"A*0247"
numeric(0)
2006 May 12
1
wilcox.exact function (PR#8856)
Full_Name: Patrick Hodgson
Version: 2.0
OS: solaris 2.9
Submission from: (NULL) (65.94.128.161)
The value reported for the parameter W in the function wilcox.exact appears to
be incorrect. I have checked the reference in the help file for this function
(Myles & Hollander 1973, as well as 2nd ed. 1999 by same authors) and it is
clear that W is the sum of the ranks of the data set with the
2009 Oct 27
1
wilcox.exact() problem
Dear R friends,
here I write again about the wilcox.exact() problem. I want to compare two sets of categorical data, and in one case it says "negative length vectors not allowed", and in the other one I get the error "cannot allocate vector of length ...".
On http://rapidshare.com/files/298621893/wilcox.exact_trouble.Rdata.html you can download the data that cause the
2002 Sep 26
1
T-Value, ties and the wilcox.test()
hi,
i am looking for a way to correct for ties in the wilcoxon signed rank
test -> e.g. wilcox.test(x,mu=.5)
one way i have heard of is to look up the p value in a table that has
been produced by Buck (1975). obviously i need to know the T-value to do
that -> how do i get the T-value from the wilcox.test() function.
is there any other (already implemented) way to correct for ties in
2019 Dec 07
2
Inconsistencies in wilcox.test
Thank you for a fast response. Nice to see this mailing list being so
alive.
Regarding Inf issue: I agree with your assessment that Inf should not be
removed. The code gave me an impression that Inf values were
intentionally removed (since is.finite() was used everywhere, except for
paired case). I will try to adjust my patch according to your feedback.
One more thing: it seems like you
2013 Dec 16
1
Power calculations for Wilcox.test
Greetings, I'm working on some analyses where I need to calculate wilcox
tests for paired samples. In my current literature search I've found a
few papers on sample size determination for the wilcox test notably:
Sample Size Determination for Some Common Nonparametric Tests
Gottfried E. Noether
Journal of the American Statistical Association
2011 Sep 28
1
Wilcox test and data collection
Dear Contributors
I have a problem with the collection of data from the results of a test.
I need to perform a comparative test over groups of data , recall the value
of the pvalue and create a table.
My problem is in the way to replicate the analysis over and over again over
subsets of data according to a condition.
I have this database, called y:
gg t1 t2 d
40 1 1