Displaying 20 results from an estimated 2000 matches similar to: "Shapiro-Wilk cpoefficients: 2 Qs"
2003 Dec 10
3
expressing functions
# Why does expressing one function
require(ctest)
t.test
# return only
function (x, ...)
UseMethod("t.test")
<environment: namespace:ctest>
# but expressing another function
shapiro.test
# returns more complete code?
function (x)
{
DNAME <- deparse(substitute(x))
x <- sort(x[complete.cases(x)])
n <- length(x)
if (n < 3 || n > 5000)
2013 Apr 06
1
Fw: Reversing data transformation
From: aguitatierra@hotmail.com
Sent: Friday, April 05, 2013 11:47 PM
To: r-help@r-project.org ; R Help
Subject: Reversing data transformation
Hi everybody,
I would be very grateful if you could give me your thoughts on the following issue.
I need to perform Box-Cox (bcPower) transformation on my data. To do this, I calculated lambda using the function 'powerTransform'.
2013 Apr 05
1
Reversing data transformation
Hi everybody,
I would be very grateful if you could give me your thoughts on the following issue.
I need to perform Box-Cox (bcPower) transformation on my data. To do this, I calculated lambda using the function 'powerTransform'.
powerTransform(data)
However, I got an error message when performing this function:
Convergence failure: return code = 52
I was told by John Fox
2000 Sep 25
1
Interpretation of Shapiro-Wilk
Can anybody tell me the exact meaning of the $statistic and $p.value
calculated by shapiro.test? Unfortunately it is not covered in my few
text books, and I cannot find the explanation in the R documentatiom or
on-line.
If I have a test statistic, T, which is Normally distributed with mean=m
and sd=s under the null hypothesis, then I can convert T to a p-value
(one-sided) using:
p <- pnorm(T,
1999 Nov 04
1
shapiro wilk
I'm pretty new to R and are trying to do some reliable normality
testing... but, can't find the Shapiro Wilk test in R Does some
experienced user have such a function that will be wanting to share with
me? Or there is maybe some other way to get hte Shapiro Wilk test
done... I'll appreciate any hint on this,
Thanks
--
***********************
Horacio Samaniego
Dep. Ecologia
P.
2001 Jul 02
2
Shapiro-Wilk test
Hi,
does the shapiro wilk test in R-1.3.0 work correctly? Maybe it does, but can
anybody tell me why the following sample doesn't give "W = 1" and
"p-value = 1":
R> x<-1:9/10;x
[1] 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
R> shapiro.test(qnorm(x))
Shapiro-Wilk normality test
data: qnorm(x)
W = 0.9925, p-value = 0.9986
I can't imagine a sample being
2008 Jan 13
1
Shapiro-Wilk
What is the formula used in Shapiro-Wilk Statistic?
Thanks
Eduardo (S?o Paulo/ Brazil)
2013 Apr 05
2
How to perform a grouped shapiro wilk test on dataframe
Hello,
I was wandering if it is possible to perform on a dataframe called 'all' a
shapiro wilk normality test for COUNTS by variable Group
ACTIVITY? Could it be done using plyer? I saw an eg that applies to an
array but not to a dataframe:
lapply(split(dataset1$Height,dataset1$Group),shapiro.test)
Any thoughts would be much appreciated.
My dataframe is in shape:
dat ACTIVIT
2008 Jul 12
5
shapiro wilk normality test
Hi everybody,
somehow i dont get the shapiro wilk test for normality. i just can?t
find what the H0 is .
i tried :
shapiro.test(rnorm(5000))
Shapiro-Wilk normality test
data: rnorm(5000)
W = 0.9997, p-value = 0.6205
If normality is the H0, the test says it?s probably not normal, doesn
?t it ?
5000 is the biggest n allowed by the test...
are there any other test ? ( i know qqnorm
2010 Apr 09
6
How to run Shapiro-Wilk test for each grouped variable?
I want to run Shapiro-Wilk test for each variable in my dataset, each
grouped by variable groupFactor.
I have these working commands:
> data.n<-names(data) # put names into a vector called data.n
> by(eval(parse(text=(paste("data",data.n[3],sep="$")))), data$factor, shapiro.test) #run shapiro.test
but I must to change the variable number manualy. How to automate
2005 Nov 09
1
Problems with Shapiro Wilk's test of normality.
Hi,
I am trying to create a table with information from Shapiro Wilk's
test of normality.
However, it fails due to lack of sample size, it says, but the way I
see it, this is not a problem.
(See the table of sample sizes (almost) at the bottom).
Applying a different function using a similar ftable call is not a
problem (See the bottom table).
This is R 2.1.0 on Linux (Gentoo).
/Fredrik
2008 Oct 09
1
interpreting Shapiro-Wilks test result
Hi all,
I am newbie in using R software and also doing statistical test. I want to know if my data in in normal distribution. I have 2 groups of data and I did calculate Shapiro Wilks using R software. Here is the results:
Group 1: W = 0.9206, p-value = 0.01683
Group 2: W = 0.9626, p-value = 0.4694
I am not quite sure what default confidence level (CF) is used in calculating Shapiro Wilks.
2008 Nov 21
1
Bug in Kendall for n<4?
> library(Kendall)
> Kendall(1:3,1:3)
WARNING: Error exit, tauk2. IFAULT = 12 <<<<<<
tau = 1, 2-sided pvalue =1
I believe Kendall tau is well-defined for this case and the reported
value is correct; isn't it a bug to give a warning? (And if, e.g.,
the pvalue is not well-defined in this case, wouldn't it be better to
return NA or NaN or something?) Also,
2010 Feb 18
1
Shapiro-Wilk test problem
Hi everybody,
Does anyone know what problem may be with this test.
I am applying 5 different normality tests and use p-values for them, but for
some reason S-W gives me NA, while sample size is 100.
Any ideas?
Thanks a lot!
[[alternative HTML version deleted]]
2005 May 03
1
multivariate Shapiro Wilks test
Hello,
I have a question about multivariate Shapiro-Wilks test.
I tried to analyze if the data I have are multivariate normal, or how
far they are from being
multivariate normal. However, any time I did
>mshapiro.test(mydata)
I get the message:
Error in solve.default(R %*% t(R), tol = 1e-18) :
system is computationally singular: reciprocal condition number
= 5.38814e-021
I tried
2008 Jul 14
0
"Reasonable doubt" - was "Re: shapiro wilk normality test"
>>> Ted Harding <Ted.Harding at manchester.ac.uk> 14/07/2008 00:16 >>>
>said:
>What constitutes "reasonable doubt" can become a very interesting
>question, but there are some crimes for which it has a definite
>statistical interpretation
Warning for potential courtgoers: "reasonable doubt" NEVER has a direct
statistical interpretation in a
2008 Mar 12
1
Problem when calling FORTRAN subroutine (dll)
Hello,
I am trying to call a FORTRAN subroutine from R. The Fortran code is @:
http://lib.stat.cmu.edu/apstat/206
It performs a bivariate isotonic regression on a rectangular grid (m X n) matrix. I used the g77 compiler and successfully created a dll file and it also loads successfully from R. But somehow the programs fails to run properly. (I do get the correct result when I compile the
2008 Apr 26
0
Consistency of m-shapiro.test
Hello all,
I tried several experiments with the mshapiro.test package in R and compared
it with the energy package to test for multivariate normality and find that
the mshapiro.test is not consistent which is a bit concerning and has
suspicious behavior. On the other hand the energy test seems to be a more
appropriate test for testing multivariate normality in any dimension. I
looked for the
2007 Jun 29
1
Shapiro Test P Value Incorrect? (PR#9768)
Full_Name: Jason Polak
Version: R version 2.5.0 (2007-04-23)
OS: Xubuntu 7.04
Submission from: (NULL) (137.122.144.35)
Dear R group,
I have noticed a strange anomaly with the shapiro.test() function. Unfortunately
I do not know how to calculate the shapiro test P values manually so I don't
know if this is an actual bug.
So, to produce the results, run the following code:
pvalues = 0;
for
2012 May 02
2
output Shapiro-Wild results to a table
Hello,
I have applied the Shapiro test to a matrix with 26.925 rows of data using the following
F1.norm<-apply(F1.n.mat,1,shapiro.test)
I would now like to view and export a table of the p and W values from the Shapiro test, but I am not sure how to approach this.
I have tried the following with errors.
> write.table(x=F1.norm,file="I:/R_Work/F1/Shapiro.csv",