Displaying 20 results from an estimated 1000 matches similar to: "function centralm - does it exist"
2011 Feb 21
3
assign value to multiple objects with a given ls pattern
Dear R colleagues,
This seems pretty straight forward but I have been banging my head on this for some time and can't seem to find a solution
suppose I have something like
a1<-1; a2<-2; a3<-3; a4<-4; b1<-3; b2<-4
I would like to quickly assign to objects with a certain pattern, e.g., those in
ls(pattern="a")
a specific value, e.g., "99", without
2007 Nov 16
1
monthplot () - axis change color
Hi,
When I run this code a part of my x-axis and y-axis changes color. Can
somebody tell me what is wrong? Also, is there a way to control the color of
the average lines?
monthplot(AirPassengers+500, ylim=c(min(AirPassengers),
max(AirPassengers+500)), ylab="")
par(new=T)
monthplot(AirPassengers, col="blue", ylim=c(min(AirPassengers),
max(AirPassengers+500)),
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]
2008 Jun 19
2
how to write symbol (nabla) in R graph
Dear colleagues,
Can anyone of you tell me how to write a "nabla" symbol in an R graph?
Thanks in advance,
Nuno
______________________________________________
Centro de Oceanografia - IO-FCUL, Portugal
Center for Quantitative Fisheries Ecology - ODU, USA
[[alternative HTML version deleted]]
2004 Sep 21
2
Ever see a stata import problem like this?
Greetings Everybody:
I generated a 1.2MB dta file based on the general social survey with
Stata8 for linux. The file can be re-opened with Stata, but when I bring
it into R, it says all the values are missing for most of the variables.
This dataset is called "morgen.dta" and I dropped a copy online in case
you are interested
http://www.ku.edu/~pauljohn/R/morgen.dta
looks like this
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
#
2005 Dec 01
2
about comparison of KURTOSIS in package: moments and fBasics
Hello
I do not know very much about statistics (and English language too :-( ),
then I come in search of a clarification (explanation):
I found two distinct results on KURTOSIS and
I do not know which of them is the correct one.
Any aid will be welcome!
klebyn
################ CODE
rnorm(1000) -> x
library(moments)
kurtosis(x)
skewness(x)
detach("package:moments")
2008 Oct 18
1
ARIMA - h-step ahead errors
Dear colleagues,
?arima? returns directly the 1-step ahead errors but I am interested in
obtaining other h-step ahead errors for several ARIMA models I have
fitted. Is there any way I can obtain this with R? Any help would be
appreciated.
Sincerely,
Nuno Prista
_________________________
CO - FCUL, Lisboa, Portugal
CQFE - ODU, Norfolk, USA
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.
--
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
2007 Apr 27
2
Jarque-Bera and rnorm()
Folks,
I'm a bit puzzled by the fact that if I generate 100,000 standard normal
variates using rnorm() and perform the Jarque-Bera on the resulting vector,
I get p-values that vary drastically from run to run. Is this expected?
Surely the p-val should be close to 1 for each test?
Are 100,000 variates sufficient for this test?
Or is it that rnorm() is not a robust random number generator?
2010 Mar 03
1
help R IRT simulation
hello R,
This is about simulation in psychomtrics in IRT in R. I want to simulate b
parameters(item difficulty) with moments of fixed values of mean, st.d,
skewness and kurtosis. Is there any specific IRT package in R with those
functions to control those moments? I have seen other programs that can
control mean and st.d but not skewness and kurtosis.
Thank you,
helen L
[[alternative HTML
2009 Nov 21
1
what do i do to fix missing packages...see error
> exampledata <- rnorm(10000)
> summary(exampledata)
Min. 1st Qu. Median Mean 3rd Qu. Max.
-4.030000 -0.666200 -0.023390 -0.009384 0.664700 4.092000
> desc <- function(mydata) {
+ require(e1071)
+ quantls <- quantile(x=mydata, probs=seq(from=0, to=1, by=0.25))
+ themean <- mean(mydata)
+ thesd <- sd(mydata)
+ kurt <-
2003 Nov 08
1
notation for skewness and kurtosis
Hello everybody,
this is a bit off topic, so maybe you can just reply to me personally...
What is the typical notation for 'skewness', 'kurtosis' and maybe 'excess
kurtosis'?
Thank you,
Martina
--------------------------------------------------------------------------
Department of Statistics Office Phone: (614) 292-1567
1958 Neil Avenue, 304E Cockins Hall
2011 Aug 06
1
significance of differences in skew and kurtosis between two groups
Dear R-users,
I am comparing differences in variance, skew, and kurtosis between two groups.
For variance the comparison is easy: just
var.test(group1, group2)
I am using agostino.test() for skew, and anscombe.test() for kurtosis. However, I can't find an equivalent of the F.test or Mood.test for comparing kurtosis or skewness between two samples.
Would the test just be a 1 df test on
2009 Dec 23
2
Mean, median and other moments
Hi!
Suppose I have a dataset as follows
pd = c(10,7,10,11,7,11,7,6,8,3,12,7,7,10,10)
I wish to calculate the mean, standard deviation, median, skewness and kurtosis i.e. regular standard statistical measures.
average = mean(pd)
stdev = sd(pd)
median = median(pd)
skew = skewness(pd)
kurt = kurtosis(pd)
Q. No (1)
How do I get these at a stretch using some R package? I came across
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 <-
2007 Nov 25
1
spec.pgram() - circularity of kernel
Hi,
I am far from experienced in both R and time series hence the question.
The code for spec.pgram() seems to involve a circularity of the kernel (see
below) yielding new power estimates to all frequencies computed by FFT.
"
if (!is.null(kernel)) {
for (i in 1:ncol(x)) for (j in 1:ncol(x)) pgram[, i,
j] <- kernapply(pgram[, i, j], kernel, circular = TRUE)
2013 Apr 17
0
R question
HI Philippos,
Try this:
dat1<- read.csv("Validation_data_set3.csv",sep=",",stringsAsFactors=FALSE) #converted to csv
str(dat1)
#'data.frame':??? 12573 obs. of? 17 variables:
# $ Removed.AGC????????????????????????????? : num? 65.67 46.17 41.26 14.09 5.38 ...
# $ Removed.SST????????????????????????????? : chr? "" "46.1658" "41.2566"
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)))