Displaying 20 results from an estimated 20000 matches similar to: "multiple operations on indexed columns"
2005 Aug 13
1
R/S-Plus/SAS yield different results for Kendall-tau and Spearman nonparametric regression
Colleagues,
I ran some nonparametric regressions in R (run in RedHat Linux), then
a colleague repeated the analyses in SAS. When we obtained different
results, I tested S-Plus (same Linux box). And, got yet different
results. I replicated the results with a small dataset:
DATA:
37.5
23
37.5
13
25
16
25
12
100
15
12.5
19
50
20
100
13
100
10
100
10
100
16
50
10
87.5
2005 Aug 18
2
kendall tau correlation test for ties: Potential error (PR#8076)
Full_Name: Dirk Koschuetzki
Version: 2.1.1
OS: source code
Submission from: (NULL) (194.94.136.34)
Hello,
>From the source code (R-2.1.1, file: .../R-2.1.1/src/library/stats/R/)
******************************
cor.test.default <-
function(x, y, alternative = c("two.sided", "less", "greater"),
method = c("pearson", "kendall",
2009 Aug 16
1
Printing the null hypothesis
Dear R developers,
Currently many (all?) test functions in R describe the alternative
hypothesis, but not the the null hypothesis being tested. For example,
cor.test:
> require(boot)
> data(mtcars)
> with(mtcars, cor.test(mpg, wt, met="kendall"))
Kendall's rank correlation tau
data: mpg and wt
z = -5.7981, p-value = 0.000000006706
alternative hypothesis: true tau is not
2004 Mar 03
1
cor(..., method="spearman") or cor(..., method="kendall") (PR#6641)
Dear R maintainers,
R is great. Now that I have that out of the way, I believe I have
encountered a bug, or at least an inconsistency, in how Spearman and
Kendall rank correlations are handled. Specifically, cor() and
cor.test() do not produce the same answer when the data contain NAs.
cor() treats the NAs as data, while cor.test() eliminates them. The
option
use="complete.obs" has
2012 Aug 20
1
Kendall package tau-a, b, and c
Hi all,
I would like to ask a question related to Kendall package. I ran Kendall
(x,y) and
saw the results. But I am not sure which tau values R reported. I have
ties in
my data set, so I want tau-b. Can anybody tell how Kendall package is
calculating tau values? I have looked at the package PDF, but I could
not find
any useful information. As long as I see from the following
link, there
2010 Feb 08
2
Incorrect Kendall's tau for ordered variables (PR#14207)
Full_Name: Marek Ancukiewicz
Version: 2.10.1
OS: Linux
Submission from: (NULL) (74.0.49.2)
Both cor() and cor.test() incorrectly handle ordered variables with
method="kendall", cor() incorrectly handles ordered variables for
method="spearman" (method="person" always works correctly, while
method="spearman" works for cor.test, but not for cor()).
In
2006 Jun 22
2
programming advice
Dear R users
I want to compute Kendall's Tau between two vectors x and y.
But x and y may have zeros in the same position(s) and I wrote the
following function to be sure to drop out those "double zeros"
"cor.kendall" <- function(x,y) {
nox <- c()
noy <- c()
#
for (i in 1:length(x)) if (x[i]!= 0 | y[i] != 0)
nox[length(nox)+1]<- x[i]
for (i in
2011 Mar 28
0
Acessing Test Outputs for Writing to a Table
Hi all,
I am trying to write a script that will compute Kendall's tau for a 75 time
series (using the Kendall package) and will then write the tau and p values
from the Kendall test to a text file table that can be read into Excel.
I am having no problem calculating Kendall's tau and the associated p value
for each time series, but I am having trouble figuring out how aggregate the
2005 Jun 28
1
faster algorithm for Kendall's tau
Hi,
I need to calculate Kendall's tau for large data
vectors (length > 100'000).
Is somebody aware of a faster algorithm or package
function than "cor(, method="kendall")"?
There are ties in the data to be considered (Kendall's
tau-b).
Any suggestions?
Regards
Ferdinand
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,
2004 Oct 14
1
correlating between two vectors of numbers
Hi, R!
Question1:
I am trying to correlate two vectors of numbers (two columns of microarray
signal values) by using the non-parametric Spearman's rank correlation
coefficient rho:
> cor.test(V2.Signal,V3.Signal,method="spearman")
but I get the error message:
Error in if (q > (n^3 - n)/6) pspearman(q - 1, n, lower.tail = FALSE) else
pspearman(q, :
missing value
2006 May 24
0
the computation of exact p-value for the nonparametric cor-test with ties
Hello,
I wuold like to propose my modifications of the original cor.test to you : I
tried to calcolate the correct p-value for Spearman and Kendall's test with
ties.
Let me know what you think.
Thanks you for your time.
Antonietta di Salvatore
test <- function(x, ...) UseMethod("test")
test.default <-
function(x, y, alternative = c("two.sided",
2008 May 05
0
kendall tau a,b,c
hi,
i have 2 lists of ranks for which i'd like to compute kendall tau.
there are ties in the ranks which (to the best of my knowledge) means i
cant use tau a but rather b or c.
how does R handle that? are ties automatically detected (using
corr.test()) and is tau b/c computed instead of tau a?
also kendall does not work when values in list 1 do not occur in list 2
(and vice versa) - how does
2012 Jun 25
2
Fast Kendall's Tau
Hello.
Has any further action been taken regarding implementing David Simcha's fast Kendall tau code (now found in the package pcaPP as cor.fk) into R-base? It is literally hundreds of times faster, although I am uncertain as to whether he wrote code for testing the significance of the parameter. The last mention I have seen of this was in 2010
2006 Sep 12
1
Kendall's tau-c
Hello,
I can't find a package which calculates Kendall's tau-c. There is the
package Kendall, but it only calcuates Kendall's tau-b.
Here is the example from
ttp://www2.chass.ncsu.edu/garson/pa765/assocordinal.htm.
cityriots <- data.frame(citysize=c(1,1,2,2,3,3),
riotsize=c(1,2,1,2,1,2), weight=c(4,2,2,3,0,4))
cityriots <- data.frame(lapply(cityriots,function(x)
2004 Jul 09
1
cor.test p-value ties
R:
I got a warning message when running the cor.test function using both
Spearman and Kendall rank correlations saying that the p-value may be
incorrect due to ties in the data. My data has 35 obs and one series has
6 pairs of ties. Does anyone know if this would likely have a great
effect on the p-values calculated.. The values look good; tau = -0.68
with p-value = 8e-9 and rho = =0.84
2005 Oct 23
1
factorizing many columns of a dataframe
Hi guys,
I have a large number of columns of a dataframe that I want to apply a common factorization to; the columns are all numeric and the factorization collapses some of these values into common groups (labels). How can I do this systematically?
Is there an analog to sapply that can pass columns as vectors to FUN?
Thanks in advance,
Gregory Gentlemen
---------------------------------
2011 Apr 18
4
splom, plotmath: how to add three lines of information with alignment?
Dear expeRts,
I would like to create a scatter plot matrix with splom(). The lower panel should
contain some additional information about the samples shown in the upper panel
plot, see the splom() call below. Now two questions came up:
(1) The lower panels show "tau" and "alpha" on top of each other. How can I plot
*three* expressions on top of each other? I tried several
2011 Mar 21
1
Kendall v MannKendall Functions
Hi,
I am running a correlation analysis on a temporal dataset. I was wondering
if you would receive the same tau and p values running the function:
MannKendall(x), where x is the dependant variable that changes with time
as you would running:
Kendall(d,x), where x is the exact same dataset as the x entered into
MannKendall and d is the date on which the observation was made (assuming
that
2005 Jun 25
2
optimization problem in R ... can this be done?
Im trying to ascertain whether or not the facilities of R are sufficient for solving an optimization problem I've come accross. Because of my limited experience with R, I would greatly appreciate some feedback from more frequent users.
The problem can be delineated as such:
A utility function, we shall call g is a function of x, n ... g(x,n). g has the properties: n > 0, x lies on the