Displaying 20 results from an estimated 11000 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
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
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,
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
 
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)
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
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,
2001 Oct 26
2
wilcox.test point estimates perverse (PR#1150)
The point estimates produced by wilcox.test are perverse (not wrong, just
brain damaged).  The Hodges-Lehmann estimator that goes with the signed
rank test is the median of the Walsh averages.  The Hodges-Lehmann estimator
that goes with the rank sum test is the median of the pairwise differences.
wilcox.test agrees except that it uses the following very peculiar definition
of "sample
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
2019 Dec 12
2
Inconsistencies in wilcox.test
>>>>> Karolis Koncevi?ius 
>>>>>     on Mon, 9 Dec 2019 23:43:36 +0200 writes:
    > So I tried adding Infinity support for all cases.
    > And it is (as could be expected) more complicated than I thought.
"Of course !"   Thank you, Karolis, in any case!
    > It is easy to add Inf support for the test. The problems start with conf.int=TRUE.
  
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
2009 Sep 08
0
feature and bug in wilcox.test
Dear Developers Team,
I have two items:
1. wilcox.test with the paired=T option appears to delete zeros 
before ranking absolute differences.
Would it be possible to add the feature of removing
zeros after ranking, which is given in Lehmann's Nonparametrics
as the preferred choice. See also Pratt (1959), JASA 54, 655-667.
It is given in wilcoxsign_test of the coin package as an
option
2011 Apr 12
2
The three routines in R that calculate the wilcoxon signed-rank test give different p-values.......which is correct?
I have a question concerning the Wilcoxon signed-rank test, and 
specifically, which R subroutine I should use for my particular dataset. 
There are three different commands in R (that I'm aware of) that calculate 
the Wilcoxon signed-rank test; wilcox.test, wilcox.exact, and 
wilcoxsign_test. When I run the three commands on the same dataset, I get 
different p-values. I'm hoping that
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$p.value
[1] 1.860340e-23
> w <- wilcox.test(c(1:50),(c(1:50)+100))
>
2009 Nov 06
2
wilcox.test returning 'NA' p-value
Hi folks, sorry for this beginner question but what means a p-value = NA on
a menn-whitney test?
v1 <- c(0.022, 0.022, 0.022, 0.022, 0.022, 0.022)
v2 <- c(0.022, 0.022, 0.022, 0.022, 0.022)
wilcox.test(v1, v2, PAIRED=FALSE)
W = 15, p-value = NA
I know that there's no statistical difference between v1 and v2, so why my
p-value is not ONE ??
Can I consider p-value= NA  as ONE ??
what i
2005 Aug 17
1
trouble with wilcox.test
I'm having trouble with the wilcox.test command in R. To demonstrate the anomalous behavior of wilcox.test, consider 
> wilcox.test(c(1.5,5.5), c(1:10000), exact = F)$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
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,
2008 Apr 30
1
What are ties? Wilcox u-test
Hi,
When I execute a Wilcox u-test on two variables I receive a warning :
'cannot compute exact p-value with ties'
- What are ties? What does this mean for my data?
- Is that a problem for significance testing?
- is there a way to overcome this problem?
I have different threads in this forum but it hard to find what the exact
meaning of this warning message is.
-- 
View this message in
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