Displaying 20 results from an estimated 10000 matches similar to: "Sample size estimation for non-inferiority log-rank and Wilcoxon rank-sum tests"
2011 Apr 13
2
Wilcoxon rank sum in unbalanced design
Hi everyone!
I need to perform a Wilcoxon rank sum test, but I have some ties and the
groups have different size also. When I deal with ties I use the
wilcox.exact function, how can I solve the different size problem using this
function?
thanks
net
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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
2010 Jun 23
3
Wilcoxon signed rank test and its requirements
Hi all,
I have a distribution, and take a sample of it. Then I compare that sample with the mean of the population like here in "Wilcoxon signed rank test with continuity correction":
> wilcox.test(Sample,mu=mean(All), alt="two.sided")
Wilcoxon signed rank test with continuity correction
data: AlphaNoteOnsetDists
V = 63855, p-value = 0.0002093
alternative hypothesis:
2005 May 16
1
Mann-Whitney & Wilcoxon Rank Sum
Hello,
I am hoping someone could shed some light into the Wilcoxon Rank Sum Test
for me? In looking through Stats references, the Mann-Whitney U-test and
the Wilcoxon Rank Sum Test are statistically equivalent. When using the
following dataset:
m <- c(2.0863,2.1340,2.1008,1.9565,2.0413,NA,NA)
f <- c(1.8938,1.9709,1.8613,2.0836,1.9485,2.0630,1.9143)
and the wilcox.test command as
2010 Nov 24
2
Wilcoxon Rank Sum in R with a multiple testing correction
Hi there,
I'm a total newbie to R. I'd like to use a Wilcoxon Rank Sum test to compare
two populations of values. Further, I'd like to do this simultaneously for
114 sets of values. The two populations are C and N. The different sets of
values have arbitrary names (I'll call them a, b, c etc). The set-up is as
follows:
a b c d ....
C 2
C 3
C 5
C 9
C 4
2007 Jun 28
1
Wilcoxon Rank Sum Test.
Dear,
I'm using R software to evaluate Wilcoxon Rank Sum Test and I' getting one
Warning message as this:
> C1dea_com
[1] 1.000 0.345 0.200 0.208 0.508 0.480 0.545 0.563 0.451 0.683 0.380 0.913
1.000 0.506
> C1dea_sem
[1] 1.000 0.665 0.284 0.394 0.509 0.721 0.545 0.898 0.744 0.683 0.382 0.913
1.000 0.970
> wilcox.test(C1dea_sem,C1dea_com, paired = TRUE, alternative =
2003 Dec 01
2
wilcoxon-pratt signed rank test in R - drug-effiacy
Hi.
I'm going to introduce the R-package for a group of medical doctors later
this week and is a little confused about there use of a test named
"willcoxon-pratt" for testing if the clinical and biochemical markers has
decreased significantly after the use of some drugs for a group of patients.
Looking into the R-functions I would in R recommand using a matched-pairs
Wilcoxon
2006 Sep 11
2
Wilcoxon Rank-Sum Test with Bonferroni's correction
Dear all,
I am trying to run Wilcoxon Rank-Sum Test with Bonferroni's
correction. I have two lists: l0, l1:
mapply(function(x,y)wilcox.test(x,y)$p.value, l0, l1)
How do I run Bonferroni's correction on mapply? Any help is much apperciated.
Thanks,
-Raj
2005 Dec 20
1
Wilcoxon Mann-Whitney Rank Sum Test in R
An earlier post had posed the question: "Does anybody know what is relation
between 'T' value calculated by 'wilcox_test' function (coin package) and
more common 'W' value?"
I found the question interesting and ran the commands in R and SPSS. The W
reported by R did not seem to correspond to either Mann-Whitney U,
Wilcoxon W or the Z which I have more
2002 Mar 20
1
Wilcoxon Rank Sum Test
How does R compute the p-value in the Wilcoxon Rank Sum Test?
If I have the test statistics, can I get the p-value using the function
pwilcox?
Thanks
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2006 Aug 25
1
exact Wilcoxon signed rank test with ties and the "no longer under development" exactRanksumTests package
Dear List,
after updating the exactRanksumTests package I receive a warning that
the package is not developed any further and that one should consider
the coin package.
I don't find the signed rank test in the coin package, only the Wilcoxon
Mann Whitney U-Test. I only found a signed rank test in the stats
package (wilcox.test) which is able to calculate the exact pvalues but
unfortunately
2009 May 19
1
Wilcoxon nonparametric p-values
When I use wilcox.test, I get vastly different p-values than the problems
from Statistics textbooks.
For example:
The following problem comes from "Applied Statistics and Probability for
Engineers", 2nd Edition, by D. C. Montgomery. Page736, problem 14.7. The
problem is to compare the sample data with a population median of 8.5. The
book answer is p = 0.25, wilcox.test answer is p =
2010 Jan 11
0
Non-inferiority log-rank test
Hi Group,
I'm looking for a method to calculate sample size for a
non-inferiority survival analysis.
Initially I've used cpower() of Hmisc, switching the roles of type-I
and type-II errors, as cpower() assumes no treatment difference as the
null hypothesis.
Now, I would like to introduce event rate difference under the
null-hypothesis, and calculate sample size accordingly. Any ideas?
2006 Dec 19
4
nonparametric significance test for one sample
Hello, Gurus:
I tried to test if the sample mean of a dataset is zero.
The data has 1500 numbers with a lot of zeros and some small
positive numbers. The data range on [0,1] but the distribution is unknown.
It is zero inflated anyway.
I tried to use the Wilcoxon Signed Ranks test. But I read from this website
that it does assume the population pdf is symmetric.
2017 Aug 22
1
Wilcoxon signed-rank test
Hi,
I am using wilcox.test function to test the difference between the means of
two samples. The data points are paired, so I am using a paired test.
There is one strange case. Sample A has a higher mean than a sample B.
However, wilcox.test function says that sample B has a significantly higher
"mean rank" than sample A. How is it possible?
Here is the code (data file is attached):
2010 Feb 08
1
Wilcoxon signed-ranks test using package coin ?
Given the following data, and hypothesized median M.0 I've found a
method to implement the Wilcoxon signed-rank test.
Data: (with one zero difference and tied ranks)
x <- c(136, 103, 91, 122, 96, 145, 140, 138, 126, 120, 99, 125,
91,142, 119, 137)
M.0 <- 119
> library(exactRankTests)
Package ?exactRankTests? is no longer under development.
Please consider using package ?coin?
2006 Sep 29
1
Wilcoxon Rank test of Package Coin
Hi,
I am running the following example which can be found on page 12 of the pdf file of COIN package
wt<-wilcox_test(pd~age,data=water_transfer,distribution="exact", conf.int=TRUE)
"wt" actually contains the estimate of difference in location and the confidence interval of it. I am just wondering how can I extract these values? From the examples, I understand that the
2010 Nov 24
3
Límites de confianza de la mediana en distribuciones simétricas
Por si alguno pudiera ayudarme.
Al realizar el t.test para una muestra, junto con el valor de t y el
p-valor, la función proporciona la estimación de la media y su INTERVALO
DE CONFIANZA.
Desde el punto de vista de la estadística de rangos esto se puede hacer
mediante:
> iris$MEDIANA <- with(iris, 2.95)
> median(iris$Sepal.Width - iris$MEDIANA, na.rm=TRUE) # median difference
[1]
2005 May 04
4
rank of a matrix
how do I check the rank of a matrix ?
say
A= 1 0 0
0 1 0
then rank(A)=2
what is this function?
thanks
I did try help.search("rank"), but all the returned help information
seem irrelevant to what I want.
I would like to know how people search for help information like this.
rank(base) Sample Ranks
SignRank(stats) Distribution of the
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