Displaying 20 results from an estimated 2000 matches similar to: "Power curve for a wilcoxon test"
2011 Sep 15
1
How to compute the power of a wilcoxon test?
Hello All,
I posted a similar question before, but the direction was driven to whether
my case is suitable for a wilcoxon test. After research about the
appropriateness, I am pretty sure that a wilcoxon test is the right tool for
my case. But how to compute the power of the test is still an unanswered
question bothering me.
The basic stats of my two paired samples are:
mean1 = 0.0032, sd1 =
2008 Apr 13
2
Arrays and functions
Hi, I' am doing a stats project using R to work out the size of a t-test and wilcoxon test depending on the distribution and sample size. I just can't get it to work - I want to put my results from the function size() into an array.At the moment I keep getting the error message:Error in res[distribution, test, samplesize] <- results : subscript out of boundsCan anyone tell me where
2009 Oct 23
4
How to apply the Wilcoxon test to a hole table at once?
Hi,
I have a data set:
> Dataset
X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17
1 user1 m 22 19 28 24 12 18 9 7 4 5 4 7 5 7 9
2 user2 f 25 19 23 18 18 15 6 8 6 6 7 10 7 7 7
3 user3 f 28 21 24 18 15 12 10 6 7 9 5 10 5 9 5
4 user4 f 26 19 26 21 12 18 6 6 5 1 3 8 6 5 6
5 user5 m 21 22 26 18 9 6 4 6 1
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
2005 Nov 14
1
effect sizes for Wilcoxon tests
Hello,
I use t.test for normal distributed and wilcox.test for non-normal
distributed samples.
It is easy to write a function for t.test that calculates the effect
size, because all parts of the formula are available from the t.test
result: r = sqrt(t*t / (t*t + df))
However, for Wilcoxon tests, the formula for effect sizes is:
r = Z / sqrt(N)
I wonder how I can calculate the Z-score in R for
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
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
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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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:
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
2012 Nov 25
2
Finding the Degrees of Freedom in a Wilcoxon Test
Dear R-ers,
I am currently running some Wilcoxon tests in R-64.
How do I find the degrees of freedom in the output I am receiving?
> wilcox.test(good$TRUE, good$x4a, paired=FALSE)
Wilcoxon rank sum test with continuity correction
data: good$TRUE and good$x4a
W = 2455, p-value < 2.2e-16
alternative hypothesis: true location shift is not equal to 0
Thank you,
Stephen.
2009 Mar 02
3
Help with Wilcoxon Test
Hi
I have 2 sets of data that I want to do a Wilcoxon test on. They are of the same dimension. One has 4 zero values and the other has 5.
> dim(SampA)
[1] 1 10
> dim(SampV)
[1] 1 10
I get the folowing error
Error in wilcox.test.default(SampA, SampV, na.rm = TRUE, paired = FALSE, :
'x' must be numeric
I am using the function
wilcox.test(SampA, SampV, na.rm=TRUE,
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 =
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
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 =
2012 Feb 16
2
Wilcoxon test p value with one decimal place
Dear list,
Let's say I have data
a=c(37.961,38.214,57.68)
b=c(77.56,61.875,67.683)
wilcox.test(a,b)
the wilcoxon test only gives me a p value with one decimal place. Is this
normal? Thanks.
Jun
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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
2007 Jun 14
1
Wilcoxon test on data matrix
Dear everyone,
I am trying to do a Wilcoxon one-sided test on my gene expression data.
These are the data i have in R:
data.matrix (matrix, numeric) containing all gene expression data (42 rows=genes, 42 columns=tumors), no column header or row names
data.cl (vector, numeric) consisting of 42 0's and 1's to indicate class 0 or class 1 for each column in data.matrix
I want to do a
2003 Feb 15
2
How to code a bootstrap version of the Wilcoxon-Mann-Whitney test (and variants)?
Hello,
can someone please help me with coding a function for a bootstrap WMW test (package boot, R under Windows, version 1.6.2)?
2012 Jul 24
2
Wilcoxon V = 0
I am running a pairwise wilcoxon signed rank test, and I am not sure how to
interpret the result. I would like to see if there is a difference between
the values in conditions a and b. It doesn't seem possible to have a V = 0,
but a significant p value. Am I doing something wrong?
The command I used is this:
wilcox.test(x=a$x,y=b$x,paired=TRUE)
The output looks like this:
Wilcoxon