Displaying 20 results from an estimated 1000 matches similar to: "Sample size calculations for one sided binomial exact test"
2003 Aug 27
4
Newbie graphing questions
Hi everyone. R is new to me and I'm very impressed with its
capabilities but still cannot figure out how to do some basic things.
There seems to be no lack of documentation but finding what I need has
proven difficult. Perhaps you can help.
Here's what I'm after:
1. How do I create a new plot without erasing the prior one i.e., have
a new window pop up with the new graph?
2000 Mar 22
4
density ellipses?
Hello,
has anybody written a function to plot density ellipses (95%, 99% or
anything) in a scatterplot? I found nothing in any package, nor in the list
archives.
There does seem to be a contributed package "ellipse" for S-Plus (on
S-Archive), but it does a lot more than what I would need. Still, if anybody
ported it to R, I'd be grateful for a link. I'm a bit afraid to try the
2011 Dec 06
2
Why can't I figure this out? :S
Hi, so I don't speak computer and I have no idea what this code is telling
the program to do, but I apparently need to be able to find and isolate
influencial observations. Problem, I have no idea what the error means and
where it may be from in the code.
error I get is below the code
{
## OLS results
NameC<- lm(gpanew~female+female:lastinit+agenew+canadian+mom_ed+yearstudy)
## default:
2008 Mar 09
1
sampsize in Random Forests
Hi all,
I have a dataset where each point is assigned to a class A, B, C, or
D. Each point is also assigned to a study site. Each study site is
coded with a number ranging between 1-100. This information is stored
in the vector studySites.
I want to run randomForests using stratified sampling, so I chose the option
strata = factor(studySites)
But I am not sure how to control the number of
2006 Jan 25
1
imbalanced classes
Hi Andy,
I know this topic has been discussed before on the R-help, but I was
wondering if you could offer some advice specific to my application.
I'm using the R random forest package to compare two classes of data,
the number of cases in each class relatively low, 28 in class 1 and 9
in class 2. I'd really like to use R environment to analyze this data,
however I'm finding it
2005 Oct 27
1
Repost: Examples of "classwt", "strata", and "sampsize" i n randomForest?
"classwt" in the current version of the randomForest package doesn't work
too well. (It's what was in version 3.x of the original Fortran code by
Breiman and Cutler, not the one in the new Fortran code.) I'd advise
against using it.
"sampsize" and "strata" can be use in conjunction. If "strata" is not
specified, the class labels will be used.
2006 Nov 13
1
random forest regression
Dear all,
I am doing a regression in ramdomForest, using the option "sampsize" reduce
the number of records used to produce the randomForest object.
The manual says "For classification, if sampsize is a vector of the length
the number of strata, then sampling is stratified by strata, and the
elements of sampsize indicate the numbers to be drawn from the strata". I
need my
2010 Jan 28
0
exactci package gives exact binomial and poisson tests and matching CI
I am announcing the release of the exactci package. It calculates exact tests and confidence intervals for binomial and Poisson tests. Here is an example to motivate the package:
Suppose you want to see if the observed rates of 2/17877 for group A are significantly different from the observed rates of 10/20000 for group B assuming Poisson counts. The poisson.test function in the stats package
2010 Jan 28
0
exactci package gives exact binomial and poisson tests and matching CI
I am announcing the release of the exactci package. It calculates exact tests and confidence intervals for binomial and Poisson tests. Here is an example to motivate the package:
Suppose you want to see if the observed rates of 2/17877 for group A are significantly different from the observed rates of 10/20000 for group B assuming Poisson counts. The poisson.test function in the stats package
2008 Jan 31
3
Log rank test power calculations
Does anyone have any ideas how I could do a power calculation for a log
rank test. I would like to know what the suggested sample sizes would
be to pick a difference when the control to active are in a ratio of 80%
to 20%.
Thanks
Dan
--
**************************************************************
Daniel Brewer, Ph.D.
Institute of Cancer Research
Email: daniel.brewer at icr.ac.uk
2009 Mar 20
2
randomForest
Hi!
I am dealing with random forest using R.
Is there a way to sample a fixed no.of rows from a dataset for use with
different trees in random Forest.
To be more clear, my data set contains 1500 rows, and I am growing 500 trees
in Random Forest
Is it possible to sample only 500 rows of data from the data set and use it
for different trees in the forest. I mean each tree of the forest should use
2005 Oct 27
1
Repost: Examples of "classwt", "strata", and "sampsize" in randomForest?
Sorry for the repost, but I've really been looking, and can't find any
syntax direction on this issue...
Just browsing the documentation, and searching the list came up short... I
have some unbalanced data and was wondering if, in a "0" v "1"
classification forest, some combo of these options might yield better
predictions when the proportion of one class is low (less
2004 Apr 30
1
Exact Binomial test feature or bug?
Dear R Users,
Is the p-value reported in a two-tailed binomial exact
test in error or is it a feature?
If it is a feature, could someone provide a reference
for its two-tailed p-value computations?
Using Blaker's (2000 - Canad. J. Statist 28: 783-798)
approach,the p-value is the minimum of the two-tailed
probabilities $P \left(Y\geq y_{obs}\right)$ and
$P\left(Y\leq y_{obs}\right)$
2007 Jan 28
2
help with RandomForest classwt option
Hello there,
I am working on an extremely unbalanced two class classification problems. I
wanna use "classwt" with "down sampling" together. By checking the rfNews()
in R, it looks that classwt is not working yet. Then I looked at the
software from Salford. I did not find the down sampling option. I am
wondering if you have any experience to deal with this problem. Do you
2005 Jul 23
2
cor(X) with P-Value
Friends
I am new to R (and statistics) so am struggling a bit.
Briefly...
I am interested in getting the P-Value from cor(X) where X is a matrix.
I have found cor.test.
Verbosely...
I have 4 vectors and can generate the corellation matrix...
> cor(cbind(X1, X2, X3, X4))
X1 X2 X3 X4
X1 1.00000000 -0.06190365 -0.156972795 0.182547517
X2
2012 Nov 24
6
IMPORTANT!!!! PLEASE HELP ME
Hi,
I want to generate 10000 samples from normal distribution with replacement
case and every sample size is 50. What should I do ?
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2009 May 13
2
Problems with randomly generating samples
Dear R users,
Can anyone please tell me how to generate a large number of samples in R, given certain distribution and size.
For example, if I want to generate 1000 samples of size n=100, with a N(0,1) distribution, how should I proceed?
(Since I dont want to do "rnorm(100,0,1)" in R for 1000 times)
Thanks for help
Debbie
2009 May 21
1
Need help on ploting Histograms
this is the command i made for a normal distribution, but when i try to plot
the histograms, i dont know why the bars don't stick on the line...
nsamples<-1000
sampsize<-15
Samples<-matrix(rnorm(nsamples*sampsize,0,1),nrow=nsamples)
a<-apply(Samples,1,var)
NC14<-a*14
x<-0:40
plot(x,dchisq(x,14),type='h')
hist(NC14,freq=F,add=T)
--
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2009 Sep 24
3
pipe data from plot(). was: ROCR.plot methods, cross validation averaging
All,
I'm trying again with a slightly more generic version of my first question. I can extract the
plotted values from hist(), boxplot(), and even plot.randomForest(). Observe:
# get some data
dat <- rnorm(100)
# grab histogram data
hdat <- hist(dat)
hdat #provides details of the hist output
#grab boxplot data
bdat <- boxplot(dat)
bdat #provides details of the boxplot
2005 Aug 03
3
clara - memory limit
Dear all,
I'm trying to estimate clusters from a very large dataset using clara but the
program stops with a memory error. The (very simple) code and the error:
mydata<-read.dbf(file="fnorsel_4px.dbf")
my.clara.7k<-clara(mydata,k=7)
>Error: cannot allocate vector of size 465108 Kb
The dataset contains >3,000,000 rows and 15 columns. I'm using a windows
computer