Displaying 20 results from an estimated 1000 matches similar to: "How to do multi-factor stratified sampling in R"
2008 Sep 26
0
Confidence interval for binomial variance
Based on simulations, I've come up with a simple function to compute
the confidence interval for the variance of the binomial variance,
where the true variance is
v = rho*(1-rho)/n
where rho = true probability of success and n = # of trials.
For x = # successes observed in n trials, p = x / n as usual.
For p < 0.25 or p > 0.75, I use the proportion-based transformed
confidence
2007 Sep 10
1
S-Plus "resample" package and associated functions
Are there any packages in R that reproduce the package "resample" of S-Plus?
The sample() function in R doesn't provide equivalent flexibility of
bootstrap() and bootstrap2().
================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: ral at lcfltd.com
Least Cost Formulations, Ltd. URL: http://lcfltd.com/
824
2008 Sep 25
1
R function which finds confidence interval for binomial variance
I need to construct confidence intervals for the binomial variance.
This is the usual estimate
v = x*(n-x)/n
or its unbiased counterpart
v' = x*(n-x)/(n-1)
where x = binomial number of successes observed in n Bernoulli trials
from proportion p.
The usual X^2 method for variance confidence intervals will not work,
because of the strong non-normal character of the sampling
2009 Sep 03
1
Problem accessing functions in package 'roxygen'
I have Vista Home with R-2.9.0, and installed and tried to test the
package 'roxygen':
> utils:::menuInstallPkgs()
trying URL
'http://lib.stat.cmu.edu/R/CRAN/bin/windows/contrib/2.9/roxygen_0.1.zip'
Content type 'application/zip' length 699474 bytes (683 Kb)
opened URL
downloaded 683 Kb
package 'roxygen' successfully unpacked and MD5 sums checked
The
2010 Jun 21
2
Singularity in simple ANCOVA problem
I'm using R 2.10.1 with the latest version of all packages (updated today).
I'm confused as to why I'm getting a hard singularity in a simple set
of experimental data:
> blots
ID Lot Age Conc
1 1 A 3 4.44
2 2 A 3 4.56
3 3 B 41 4.03
4 4 B 41 4.57
5 5 C 229 4.49
6 6 C 229 4.66
7 7 D 238 3.88
8 8 D 238 3.93
9 9 E 349 4.43
10 10 E 349
2008 Apr 22
2
Multidimensional contingency tables
How does one ideally handle and display multidimenstional contingency
tables in R v. 2.6.2?
E.g.:
> prob1<- data.frame(victim=c(rep('white',4),rep('black',4)),
+ perp=c(rep('white',2),rep('black',2),rep('white',2),rep('black',2)),
+ death=rep(c('yes','no'),4), count=c(19,132,11,52,0,9,6,97))
> prob1
victim perp
2008 Apr 10
1
Problem installing and using package "tseries"
I have R 2.6.2, and have tried downloading and installing the package
"tseries". I get the same error when I use two different mirror sites:
> utils:::menuInstallPkgs()
trying URL
'http://cran.mirrors.hoobly.com/bin/windows/contrib/2.6/tseries_0.10-14.zip'
Content type 'application/zip' length 400799 bytes (391 Kb)
opened URL
downloaded 391 Kb
package
2009 Jul 02
1
Getting identify() to work with lattice::cloud()
I don't seem to be able to put any syntax into identify() that gets
it to work with "lattice" cloud() graph:
layout(1)
require('lattice')
cloud(g3 ~ g1 + g2, data=gapp, col = "blue",
xlab='G1 Score', ylab='G2 Score',
zlab='G3 Score', main='3D Plot for Applicants')
identify(gapp[,2:4], labels=gapp$ID)
Here g1 is gapp[,2], g2
2007 Jun 08
1
glm() for log link and Weibull family
I need to be able to run a generalized linear model with a log() link
and a Weibull family, or something similar to deal with an extreme
value distribution.
I actually have a large dataset where this is apparently necessary.
It has to do with recovery of forensic samples from surfaces, where
as much powder as possible is collected. This apparently causes the
results to conform to some type
2007 May 27
1
How to reference or sort rownames in a data frame
As I was working through elementary examples, I was using dataset
"plasma" of package "HSAUR".
In performing a logistic regression of the data, and making the
diagnostic plots (R-2.5.0)
data(plasma,package='HSAUR')
plasma_1<- glm(ESR ~ fibrinogen * globulin, data=plasma, family=binomial())
layout(matrix(1:4,nrow=2))
plot(plasma_1)
I find that data points
2008 Jun 30
3
Is there a good package for multiple imputation of missing values in R?
I'm looking for a package that has a start-of-the-art method of
imputation of missing values in a data frame with both continuous and
factor columns.
I've found transcan() in 'Hmisc', which appears to be possibly suited
to my needs, but I haven't been able to figure out how to get a new
data frame with the imputed values replaced (I don't have Herrell's book).
Any
2008 Aug 25
1
Specifying random effects distribution in glmer()
I'm trying to figure out how to carry out a Poisson regression fit to
longitudinal data with a gamma distribution with unknown shape and
scale parameters.
I've tried the 'lmer4' package's glmer() function, which fits the
Poisson regression using:
library('lme4')
fit5<- glmer(seizures ~ time + progabide + timeXprog +
offset(lnPeriod) + (1|id),
data=pdata,
2007 Jul 23
0
Conditional logistic regression on n:m matched "cohort" data
I am designing an interlaboratory validation study for a
presence/absence alternative method test kit vs. a presence/absence
reference method test kit.
There will be 10 laboratories conducting tests using both methods. In
each laboratory, there will be 5 specimens tested, each of the 5
specimens twice by both methods (alternative, standard).
The total number of data are 10 x 5 x 4 = 200.
2007 Apr 25
0
Use of Lexis function to convert survival data to counting format
I'm trying to convert a dataset from the time-independent analysis form
> head(addicts)
id clinic status survtime prison meth clinic01
1 1 1 1 428 0 50 1
2 2 1 1 275 1 55 1
3 3 1 1 262 0 55 1
into the "counting data format" necessary to perform extended Cox regression.
I got
2007 May 28
0
Curve crosses back to origin in plot
Another sample problem: In the Windows version of R-2.5.0,
data(GHQ,package='HSAUR')
layout(1)
GHQ_glm_1<- glm(cbind(cases,non.cases) ~ GHQ, data=GHQ, family=binomial())
summary(GHQ_glm_1)
yfit_glm_1<- predict(GHQ_glm_1, type='response')
layout(1)
plot(probs ~ GHQ,pch=1,col=1,ylab='Probability(Case)', data=GHQ)
lines(yfit_glm_1 ~ GHQ, pch=3,col=3, data=GHQ)
2007 Jul 23
0
Conditional logistic regression on n:m matched "cohort" data [Corrected]
[Corrected the model formula to include "method".]
I am designing an interlaboratory validation study for a
presence/absence alternative method test kit vs. a presence/absence
reference method test kit.
There will be 10 laboratories conducting tests using both methods. In
each laboratory, there will be 5 specimens tested, each of the 5
specimens twice by both methods (alternative,
2007 Oct 18
0
Getting 'tilting' confidence intervals in R
I am trying to compute bootstrap confidence intervals for a sample
using R 2.5.1 for Windows.
I can get "Normal", "Basic", "Percentile", "BCa" and "ABC" from
boot.ci() and boot() in the Davison & Hinkley "boot" package.
But I can't figure out how to use tilt.boot() to get the "tilting"
confidence interval.
2009 Sep 08
0
Confusion on use of permTS() in 'perm'
Consider the following simple example using R-2.9.0 and 'perm' 2.9.1:
> require('perm')
> p<- c(15,21,26,32,39,45,52,60,70,82)
> g<- c('y','n','y','y', rep('n',6)) #Patients ranked 1,3,4 receive treatment
> permTS(p ~ g, alternative = 'two.sided', method='exact.ce') #find
p-value by complete enumeration
2012 Oct 08
0
Mininum number of resamples required to do BCa bootstrap?
I'm using R 2.15.1 on a 64-bit machine with Windows 7 Home Premium
and package 'boot'.
I've found that using a number of bootstrap resamples in boot() that
is less than the number of data results in a fatal error. Once the
number of resamples meets or exceeds the number of data, the error disappears.
Sample problem (screwy subscripted syntax is a relic of edited down a
more
2012 Oct 02
0
Possible error in BCa method for confidence intervals in package 'boot'
I'm using R 2.15.1 on a 64-bit machine with Windows 7 Home Premium.
Sample problem (screwy subscripted syntax is a relic of edited down a
more complex script):
> N <- 25
> s <- rlnorm(N, 0, 1)
> require("boot")
Loading required package: boot
> v <- NULL # hold sample variance estimates
> i <- 1
> v[i] <- var(s) # get sample variance
>