Displaying 20 results from an estimated 6000 matches similar to: "One Sample Nonparametric"
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 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.
2010 Mar 05
4
Nonparametric generalization of ANOVA
My interpretation of the relation between 1-way ANOVA and Wilcoxon's
test (wilcox.test() in R) is the following.
1-way ANOVA is to test if two or multiple distributions are the same,
assuming all the distributions are normal and have equal variances.
Wilcoxon's test is to test two distributions are the same without
assuming what their distributions are.
In this sense, I'm wondering
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
2007 Mar 04
1
- Nonparametric variance test
Hi useRs,
can a variance test for 2 non-normal samples be tested in R? Also, thus
far I have not been able to find the Friedman two way analysis of variance.
For normal r.v., the var.test is available, but are there any tests
available for non-normal samples?
Thanks!
Bernd
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
2012 May 29
2
Wilcoxon-Mann-Whitney U value: outcomes from different stat packages
Given this example
#start code
a<-c(0,70,50,100,70,650,1300,6900,1780,4930,1120,700,190,940,
760,100,300,36270,5610,249680,1760,4040,164890,17230,75140,1870,22380,5890,2430)
b<-c(0,0,10,30,50,440,1000,140,70,90,60,60,20,90,180,30,90,
3220,490,20790,290,740,5350,940,3910,0,640,850,260)
wilcox.test(a, b, paired=FALSE)
#sum of rank for first sample
sum.rank.a <-
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
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]
2006 Apr 27
1
Looking for an unequal variances equivalent of the Kruskal Wallis nonparametric one way ANOVA
Well fellow R users, I throw myself on your mercy. Help me, the unworthy,
satisfy my employer, the ungrateful. My feeble ramblings follow...
I've searched R-Help, the R Website and done a GOOGLE without success for a
one way ANOVA procedure to analyse data that are both non-normal in nature
and which exhibit unequal variances and unequal sample sizes across the 4
treatment levels. My
2010 Feb 02
0
Recommendations on nonparametric statistical inference textbooks
Could somebody recommend some good nonparametric statistical inference
textbooks for a beginner? And what are pros and cons of each book?
Nonparametric statistical methods by Hollander seems to be more
difficult for a beginner, but is great as a reference, right? Are
there any books that are easier to learn than Hollander's?
Also, I see some books in the wiki page. I don't find the
2008 Feb 26
4
numeric format
Hi!
I'm an R newbie and this should be a trivial problem, but I can't make it
work and cannot find what I'm doing wrong in the literature.
I entered the the command:
table<-data.frame(x, scientific=F, digits=4)
table
This prints a column of x with 16 useless decimal places after the decimal
point. Also, it prints an unwanted index number (1-20) in the left column.
How do I get rid
2010 Aug 17
3
Weird differing results when using the Wilcoxon-test
Hi,
I became a little bit confused when working with the Wilcoxon test in R.
As far as I understood, there are mainly two versions:
1) wilcox.test{stats}, which is the default and an approximation, especially,
when ties are involved
2) wilcox_test{coin}, which does calculate the distribution _exactly_ even,
with ties.
I have the following scenario:
#---BeginCode---
# big example
size = 60
2009 Sep 07
1
Equivalence of Mann-Whitney test and Kruskal-Wallis test with k=2
Hi all,
The Kruskal-Wallis test is a generalization of the two-sample Mann-Whitney
test to *k* samples. That being the case, the Kruskal-Wallis test with *k*=2
should give an identical p-value to the Mann-Whitney test, should it not?
x1<-c(1:5)
x2<-c(6,8,9,11)
a<-wilcox.test(x1,x2,paired=FALSE)
b<-kruskal.test(list(x1,x2),paired=FALSE)
a$p.value
[1] 0.01587302
b$p.value
[1]
2010 Feb 22
2
Siegel-Tukey test for equal variability (code)
Hi, I recently ran into the problem that I needed a Siegel-Tukey test for
equal variability based on ranks. Maybe there is a package that has it
implemented, but I could not find it. So I programmed an R function to do
it. The Siegel-Tukey test requires to recode the ranks so that they express
variability rather than ascending order. This is essentially what the code
further below does. After the
2009 May 18
4
MAC OSX vs Win XP: Different stats test results!
Hi all,
I wondered whether anyone has some advice on a stats-related 'sanity check',
as I ran a nonparametric multivariate test (mulrank function as decribed by
R. Wilcox, 2005) on both systems, but got different results (please see
below for the system-specific outputs)! The functions I used are attached as
well. Any advice would be much appreciated! Thanks in advance for getting
back to
2012 Jan 10
4
2 sample wilcox.test != kruskal.test
Hello,
I think I am right in saying that a 2 sample wilcox.test is equal to a 2
sample kruskal.test and
a 2 sample t.test is equal to a 2 sample anova. This is also stated in the
?kruskal.test man page:
The Wilcoxon rank sum test (wilcox.test) as the special case for two
samples; lm together with anova for performing one-way location analysis
under normality assumptions; with Student's t
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 Jul 14
1
Wilcox.test U values
I have been examining the Mann-Whitney test closely. And there are two
features of the R implementation that puzzles me. The test statistic is
reported as "W" and depends on the order of the arguments to the function.
> x <- c(1,3,5,7,9)
> y <- x-1
> x
[1] 1 3 5 7 9
> y
[1] 0 2 4 6 8
> wilcox.test(x, y)$statistic
W
15
> wilcox.test(y,x)$statistic
W
10
2006 Mar 14
2
Hodges-lehmann test and CI/significance
Does anyone know of an implementation in R of the Hodges-Lehmann
nonparametric difference between two groups? I am interested in the
estimate of the difference and the CI or significance of that difference. I
did some quick searching and didn't see it, but I may not have been looking
for the right name, etc.
Thanks,
Sean