Displaying 20 results from an estimated 4000 matches similar to: "factorial analysis influenced by data skewness"
2008 Jun 27
1
Yule Kendall resistant measure of skewness
Dear R Users,
Is anyone aware of a package which calculates the Yule Kendall resistant
(to errors,outliers) measure of skewness ? An easy calculation to perform,
but was just wondering if a package exists (as the contents of that
package would probably include other cool things I would also be
interested).
Thanks,
Tolga
Generally, this communication is for informational purposes only
and it
2009 Nov 08
0
Repeated measures on a factorial unbalanced in a blocks with split-plot design
Dear all,
I am trying to analyze data from an experiment like this:
Factors:
Hormone - Levels: SH, CH (S = without; C=with; H=Hormone)
Time - Levels: 19/08/09, 04/09/09, 18/09/09, 08/10/09, 20/10/09 (DD/MM/YY)
Nutrition - Levels: Completa, Sem (without)
Macronutrition - Levels: Ca, K, Mg, P, Sem (without)
Time is the measures day. It reflect the days after germination.
Blocks : 4
plants per
2008 Sep 23
3
Generating series of distributions with the same skewness and different kurtosis or with same kurtosis and different skewness?
Dear R users,
I hope to explain the concepts of skewness and kurtosis by generating
series of distributions with same skewness and different kurtosis or with
same kurtosis and different skewness, but it seems that i cannot find the
right functions.
I have searched the mailing list, but no answers were found.
Is it possible to do that in R? Which function could be used?
Thanks a lot.
--
2013 Feb 13
2
e1071::skewness and psych::skew return NaN
Hello everyone,
Does anyone know what would cause the skewness() function (from
e1071), as well as skew() from psych, to return a value of NaN?
I have a vector of positively-skewed data
(https://docs.google.com/file/d/0B6-m45Jvl3ZmYzlHRVRHRURzbVk/edit?usp=sharing)
which these functions return a value for like normal:
> skewness( data ) # returns 1.400405
but when I instead give those
2006 Sep 08
1
Computing skewness and kurtosis with the moments package
Hi,
I'm a newcomer to R, having previously used SPSS. One problem I have
run into is computing kurtosis. A test dataset is here:
http://www.whinlatter.ukfsn.org/2401.dat
> library(moments)
> data <- read.table("2401.dat", header=T)
> attach(data)
> loglen <- log10(Length)
With SPSS, I get
Skewness -0.320
Kurtosis -1.138
With R:
> skewness(loglen)
[1]
2011 Mar 01
1
Pairwise T-Tests and Dunnett's Test (possibly using multcomp)
Hello Everyone,
I've been learning to use R in my spare time over the past several months. I've read about 7-8 books on the subject. Lately I've been testing what I've learned by trying to replicate the analyses from some of my SAS books. This helps me make sure I know how to use R properly and also helps me to understand how the two programs are similar and different.
Below is
2011 Oct 25
1
alternative option in skewness and kurtosis tests?
I have a question about the D'Agostino skewness test and the Anscombe-Glynn
kurtosis test.
agostino.test(x, alternative = c("two.sided", "less", "greater"))
anscombe.test(x, alternative = c("two.sided", "less", "greater"))
The option "alternative" in those two functions seems to be the null
hypothesis. In the output, the
2004 Aug 24
0
How to get Dunnett's table value?
Hi,
I want to retrieve a value in the Dunnett's tables.
I know the comparisons type, the percent of level,the number of traitments
and the degrees of freedom.
Is there a function to retrieve this value with this?
Laurent Houdusse
Analyste Programmeur
2005 Jan 17
3
Skewness test
Hi,
is there a test for the H0 skewness=0 (or with skewness as test
statistic and normality as H0) implemented in R?
Thank you,
Christian
***********************************************************************
Christian Hennig
Fachbereich Mathematik-SPST/ZMS, Universitaet Hamburg
hennig at math.uni-hamburg.de, http://www.math.uni-hamburg.de/home/hennig/
2008 Sep 12
0
Skewness
I would like to know about the skewness function bundled in fBasics package.
Is it population measure of skewness or sample estimate?
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2001 Oct 03
0
Summary : Generate random data from dist. with 0 skewness and some kurtosis
Thanks to all who response my problem. Here are my summary :
1. from Dirk Eddelbuettel <edd at debian.org>
We could try a mixture of normals -- ie flip a coin (use a uniform with
some cutoff c where 0 < c < 1 ) to choose between N(0, sigma_1) and N(0,
sigma_2).
2. from Michaell Taylor <michaell.taylor at reis.com>
We could use the gld library to specify the lambdas of
1999 Jul 28
1
skewness, kurtosis
Dear R-Users and Developpers,
Currently R does not include functions to compute the skewness and
kurtosis. I programmed it myself in the following way, but probably
*real* programmers/statisticians can do that better:
mykurtosis <- function(x) {
m4 <- mean((x-mean(x))^4)
kurt <- m4/(sd(x)^4)-3
kurt
}
myskewness <- function(x) {
m3 <- mean((x-mean(x))^3)
skew <-
2013 Mar 31
0
Skewness of fitted mixture not correct?
I fitted a gaussian mixture to my financial data. The data can be found
here: http://uploadeasy.net/upload/32xzq.rar
I look at the density with
plot(density(dat),col="red",lwd=2)
this has a skew of
library(e1071)
skewness(dat)
-0.1284311
Now, I fit a gaussian mixture according to:
f(l)=πϕ(l;μ1,σ21)+(1−π)ϕ(l;μ2,σ22)
with:
2005 May 23
3
skewness and kurtosis in e1071 correct?
I wonder whether the functions for skewness and kurtosis in the e1071
package are based on correct formulas.
The functions in the package e1071 are:
# --------------------------------------------
skewness <- function (x, na.rm = FALSE)
{
if (na.rm)
x <- x[!is.na(x)]
sum((x - mean(x))^3)/(length(x) * sd(x)^3)
}
# --------------------------------------------
and
#
2004 Aug 13
5
simtest for Dunnett's test
Hi!
I use simtest fonction of multcomp package to compile a Dunnett's test.
I have 10 treatments and one control group, so i create a matrix with:
m<-matrix(0,10,11)
m[1,1]<--1
m[1,2]<-1
m[2,1]<--1
m[2,3]<-1
m[3,1]<--1
m[3,4]<-1
m[4,1]<--1
m[4,5]<-1
m[5,1]<--1
m[5,6]<-1
m[6,1]<--1
m[6,7]<-1
m[7,1]<--1
m[7,8]<-1
m[8,1]<--1
m[8,9]<-1
2004 Oct 27
2
Skewness and Kurtosis
Hi,
in which R-package I could find skewness and kurtosis
measures for a distribution?
I built some functions:
gamma1<-function(x)
{
m=mean(x)
n=length(x)
s=sqrt(var(x))
m3=sum((x-m)^3)/n
g1=m3/(s^3)
return(g1)
}
skewness<-function(x)
{
m=mean(x)
me=median(x)
s=sqrt(var(x))
sk=(m-me)/s
return(sk)
}
bowley<-function(x)
{
q<-as.vector(quantile(x,prob=c(.25,.50,.75)))
2004 Feb 09
2
moments, skewness, kurtosis
I checked the help and the mailing list archives, but I can
find no mention of a routine that calculates higher
moments like skewness and kurtosis. Of course, these
are easy enough to write myself, but I was thinking
that they MUST be in here. Am I wrong?
Thanks.
-Frank
2006 Apr 10
2
how to figure out "skewness"
I think it is simply, but I cannot find the method to figure out "skewness".
Thanks!
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2001 Sep 28
1
Generate rand. data with zero skewness and some kurtosis
Dear all,
Right now, I'm doing research about outlier in statistical data
(univariate and multivariate) and I want to simulate its behavior. My
problem is :
How to generate random data from distribution with zero skewness and
some kurtosis values in R ?
A. Kudus
=====================
Dept. of Statistics
Bandung Islamic University
I n d o n e s i a
==========================
2003 Jun 15
0
Summary: Factorial function in R
Thanks to Martin, Marc, Dennis, Rashid and Bill for comment.
The short answer is there is no factorial function within the base
package, so use the result that gamm(x + 1) = x!. This what the
factorial() function in the package gregmisc does:
factorial <- function (x) gamma(1 + x)
Bill V. also writes:
"Your best move is usually to use the lgamma() function (for log gamma)
and do