Displaying 20 results from an estimated 2000 matches similar to: "Sampling distribution of the range statistic"
2008 Feb 01
3
Converting a character string into an object variable
R-helpers:
Assume that I want to create a series of sequentially named R objects. For
example, I might want to call these objects V1, V2, V3 ... V50. To do this,
I thought of some sort of looping function like:
input.value <- seq(1:50) * 3
for(i in 1:50){
paste("V", i, sep="") <- input.value[i]
}
Of course this loop will not work since the paste function
2007 Apr 20
3
Opinion on R plots: connecting X and Y
Attention R users, especially those that are experienced enough to be
opinionated, I need your input.
Consider the following simple plot:
x <- rnorm(100)
y <- rnorm(100)
plot(x, y, bty='n')
A colleague (and dreaded SAS user) commented that she thought that my
plots could be "cleaned up" by connecting the X and Y axes. I know that
I can do that with bty='l' but I
2006 Oct 31
3
Missing data analysis in R
I am looking for a book that discusses the theory of multiple imputation
(and other methods of dealing with missing data) and, just as
importantly, how to implement these methods in R or S-Plus. Ideally,
the book would have a structure similar to Faraway (Regression),
Pinheiro&Bates (Mixed Effects) and Wood (GAMs) and would be very modern
(i.e. published within the last couple of years).
2011 Feb 28
3
Measuring correlations in repeated measures data
R-helpers:
I would like to measure the correlation coefficient between the repeated measures of a single variable that is measured over time and is unbalanced. As an example, consider the Orthodont dataset from package nlme, where the model is:
fit <- lmer(distance ~ age + (1 | Subject), data=Orthodont)
I would like to measure the correlation b/t the variable "distance" at
2007 Apr 20
2
Using power.t.test over a range of conditions
R-Helpers:
I would like to perform sample size calculations for an experiment. As
part of this process, I would like to know how various assumptions
affect the sample size calculation. For instance, one thing that I
would like to know is how the calculated sample size changes as I vary
the difference that I would like to detect. I tried the following
first, but got the associated error
2007 Jan 12
7
Making TIFF images with rtiff
Many medical journals and publishers require that images, whether
photographs or line art, be submitted as high resolution .TIFF images.
One option for R users is to produce an image in one format and to
convert it to a .TIFF file using a second software program. My
experience has been that this option often results in images of poorer
quality, often with blurry contours, and a loss of
2007 Apr 12
3
Putting 2 breaks on Y axis
R plotting experts:
I have a bivariate dataset composed of 300 (x,y) continuous datapoints.
297 of these points are located within the y range of [0,10], while 2
are located at 20 and one at 55. No coding errors, real outliers.
When plotting these data with a scatterplot, I obviously have a problem.
If I plot the full dataset with ylim = c(0,55), then I cannot see the
structure in the data in
2006 Nov 03
6
Import problem with S-Plus 7.0 dataset
I am running R 2.3.1 on a Windows XP machine. I am trying to import
some data into R that is stored as an S-Plus 7.0 .sdd file.
When I run the following command, I get this error:
> library(foreign)
> d <- read.S(file='H:\\Research\\data.sdd')
Error in read.S(file = "H:\\Research\\data.sdd") :
not an S object
The dataset is fairly large, roughly 13000 rows
2006 Nov 03
6
Import problem with S-Plus 7.0 dataset
I am running R 2.3.1 on a Windows XP machine. I am trying to import
some data into R that is stored as an S-Plus 7.0 .sdd file.
When I run the following command, I get this error:
> library(foreign)
> d <- read.S(file='H:\\Research\\data.sdd')
Error in read.S(file = "H:\\Research\\data.sdd") :
not an S object
The dataset is fairly large, roughly 13000 rows
2008 Jan 21
3
'matrix' returns integer instead of decimal
R-helpers:
I am experiencing some odd behavior with the 'matrix' function that I have
not experienced before and was wondering if there is something that I was
missing in my code.
---------------------------------
> sessionInfo()
R version 2.6.1 (2007-11-26)
i386-pc-mingw32
locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
States.1252;LC_MONETARY=English_United
2007 Mar 13
1
Freeman-Tukey arcsine transformation
R-Experts:
Does anyone know if there are R functions to perform the Freeman-Tukey
double arcsine transformation and then backtransform it?
Thanks,
Brant Inman
Mayo Clinic
2007 Jan 05
1
Calling "confint.glm" from within another function
On July 12, 2004 Spencer Graves wrote an email describing essentially
the same issue that I would like help on: calling the confint function
from within another homemade function. Because he provided many good
examples of the problem, I will not reproduce them here but will instead
refer readers to the original posting:
http://www.mail-archive.com/r-help at stat.math.ethz.ch/msg23826.html
It is
2007 Jan 06
2
Using VGAM's vglm function for ordinal logistic regression
R-Experts:
I am using the vglm function of the VGAM library to perform proportional
odds ordinal logistic regression. The issue that I would like help with
concerns the format in which the response variable must be provided for
this function to work correctly. Consider the following example:
------
library(VGAM)
library(MASS)
attach(pneumo)
pneumo # Inspect the format of the original dataset
2011 Jan 17
1
Replacing rows in a data frame
R-helpers,
Below is a simple example of some output that I am getting while trying to work with a data frame in R 2.12.1 for Mac.
-----
> testdat <- data.frame(matrix(ncol=10, nrow=10))
> colnames(testdat) <- c('a','b','c','d','e','f','g','h','i','j')
> testdat[seq(1,10,3),] <-
2010 Nov 17
1
Error: package 'pcvsuite' was built before R 2.10.0: please re-install it
R-helpers,
I have had difficulty installing the "pcvsuite" package on R version 2.12.0 (2010-10-15). The pcvsuite package is not available on CRAN, but is located for download at the following website at the University of Washington:
Windows version
http://labs.fhcrc.org/pepe/dabs/pcvsuite_1.0.zip
Mac version
2007 Apr 25
1
prelim.norm() function not working
R-experts:
I am trying to reproduce some of Paul Allison's results in his little
green book on missing data (Sage 2002). The dataset for which I am
having problems, "usnews", can be found at:
http://www.ats.ucla.edu/stat/books/md/default.htm. I am working on a
Windows machine with R 2.5 installed, all packages up-to-date.
The problem has to do with the prelim.norm() function of the
2007 May 02
1
? R 2.5.0 alpha bug
This email is intended to highlight 2 problems that I encountered
running R 2.5.0 alpha on a Windows XP machine.
#1 - Open script error
If I click the "Open folder" icon on the toolbar, R opens my script
files perfectly. However, when I select "File > Open Script >
MyFileLocation", I get a fatal error that causes R to close immediately.
This error was reproduced on 3
2010 Nov 28
1
predict.drm not generating confidence intervals
R-helpers,
I recently submitted a help request for the predict.drm function found in the drc package. I am still having issues with the function and I am submitting reproducible code hoping that somebody can help me figure out what is going on.
--------
library(drc)
# Fit a 4 parameter logistic model to ryegrass dataset
fit <- drm(rootl ~ conc, data = ryegrass, fct = LL.4())
summary(fit)
#
2006 Oct 27
1
Censored Brier Score and Royston/Sauerbrei's D
System: R 2.3.1 on a Windows XP computer.
I am validating several cancer prognostic models that have been
published with a large independent dataset. Some of the models report a
probability of survival at a specified timepoint, usually at 5 and 10
years. Others report only the linear predictor of the Cox model.
I have used Harrell's c index for censored data (rcorr.cens) as a
measure of
2006 Nov 13
3
Profile confidence intervals and LR chi-square test
System: R 2.3.1 on Windows XP machine.
I am building a logistic regression model for a sample of 100 cases in
dataframe "d", in which there are 3 binary covariates: x1, x2 and x3.
----------------
> summary(d)
y x1 x2 x3
0:54 0:50 0:64 0:78
1:46 1:50 1:36 1:22
> fit <- glm(y ~ x1 + x2 + x3, data=d, family=binomial(link=logit))
>