Displaying 20 results from an estimated 7000 matches similar to: "bias of a boot statistic"
2011 Oct 13
1
bootstrap means by strata
All -
I have an uneven set of replicates and would like to sample from this set X number of times to generate a mean for each grouping variable. I was thinking the boot package would be the thing to use, but now I'm not so sure ... given the discussion here:
http://finzi.psych.upenn.edu/Rhelp10/2010-June/243828.html
Given these data (a small subset):
> dput(x)
structure(list(numSpp
2004 Jun 15
1
Parsing results from boot
This probably has a super easy answer...but I claim newbie status! (I did
search help lists but this question is hard to isolate keyword-wise)
Basically, I'm trying to figure out how to parse the results from executing
boot(). I'm mainly interested in assigning the standard error estimate to a
scalar variable.
For example:
--------------------------------------------------------------
2004 Jun 25
1
trouble using boot package
Hello,
I am trying to carry out a bootstrap analysis (using the boot package) on a
table and cannot work out how to get the results I need!
I have a table ("d2") with 4 columns: "ID_code", "Age", "Quarter" and
"StomWt". Age (0-5) and Quarter (1-4) are my strata
Therefore I wish to estimate the confidence intervals for the mean StomWt
for each Age
2004 Apr 01
5
boot question
What in the world am I missing??
> x<-rnorm(20)
> mean(x)
[1] -0.2272851
> results<-boot(x,mean,R=5)
> results[2]
$t
[,1]
[1,] -0.2294562
[2,] -0.2294562
[3,] -0.2294562
[4,] -0.2294562
[5,] -0.2294562
Jeff Morris
Ortho-Clinical Diagnostics
A Johnson & Johnson Co.
Rochester, NY
Tel: (585) 453-5794
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2005 Aug 29
2
reexpand a matrix after subsetting
Hi,
suppose I have a matrix (or dataframe)
as a result from subsetting.
mat <- matrix(1:20,ncol=2)
mat[c(3,6,9),] <- NA
cc <- complete.cases(mat)
sub <- mat[cc,,drop=FALSE]
sub <- sub * 2
#some caluculations with sub.
now I would like to expand sub somehow
so row 3,6, and 9 would be filled with
NAs but the rest should be in place again.
Is there a simple function for this?
2004 Jul 26
1
group definition for a bootstrap
Hi,
This is probably really simple, but I am clearly not R-minded, I have read
the help files, and reread them, and I still can't work out what to do...
I have a data frame (d) with 3 columns (age (0-5), quarter (1-4) and x).
I want to estimate the precision of my mean x by age and quarter, so I want
to carry out a bootstrap for each group.
I am trying to do this within a loop, so I don't
2006 Jul 10
1
How can I obtain the values of BIAS and STD. ERROR from a bootstrap.
R 2.3.1
Windows XP
Question: How can I obtain the values of BIAS and STD. ERROR from a
bootstrap.
Background:
I am running a bootstrap:
result2<-boot(1:400,regSEvssample,R=5000)
and obtain the following results:
Bootstrap Statistics :
original bias std. error
t1* 1.876602 -0.0001368616 0.1630380
I would like to get the values of ORIGINAL and BIAS. I can get the
value of
2006 Apr 05
1
Combination of Bias and MSE ?
Dear R Users,
My question is overall and not necessarily related to R.
Suppose we face to a situation in which MSE( Mean Squared Error) shows desired results but Bias shows undesired ones, Or in advers. How can we evaluate the results. And suppose, Both MSE and Bias are important for us.
The ecact question is that, whether there is any combined measure of two above metrics.
Thank you so
2012 Jun 25
1
cannot use simple=TRUE in boot
I am doing boot with a large database, thus want to use?simple=TRUE to
reduce the memory used.
I alreday set up sim="ordinary", stype="i" , but I don't know how to
set "n=0". In fact, I don't know what does "n=0" mean?
For example,
a<-c(1:1000)
b<-c(2:1001)
c<-cbind(a,b)
library(boot)
table<-function(c,indices){
d<-c[indices,]
2012 Oct 26
1
Gini with bias correction
Hey there,
I was wondering if someone could tell me if there's a package or command
that allows me to compute a GINI coefficient using a vector of weights.
Also the coefficient should be bias corrected.
Diego Rojas
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2017 Aug 16
1
Bias-corrected percentile confidence intervals
Hi folks,
I'm trying to estimate bias-corrected percentile (BCP) confidence
intervals on a vector from a simple for loop used for resampling. I am
attempting to follow steps in Manly, B. 1998. Randomization, bootstrap
and monte carlo methods in biology. 2nd edition., p. 48. PDF of the
approach/steps should be available here:
https://wyocoopunit.box.com/s/9vm4vgmbx5h7um809bvg6u7wr392v6i9
If
2018 Sep 19
2
Bias in R's random integers?
El mi?., 19 sept. 2018 a las 14:43, Duncan Murdoch
(<murdoch.duncan at gmail.com>) escribi?:
>
> On 18/09/2018 5:46 PM, Carl Boettiger wrote:
> > Dear list,
> >
> > It looks to me that R samples random integers using an intuitive but biased
> > algorithm by going from a random number on [0,1) from the PRNG to a random
> > integer, e.g.
> >
2003 Dec 11
2
read.spss question warning compression bias
Hello again
I have a file from SPSS in .sav format.
when I run
library(foreign)
cvar<-as.data.frame(read.spss("c:\\NDRI\\cvar\\data\\cvar2rev3.sav"))
I get a warning
Warning message:
c:\NDRI\cvar\data\cvar2rev3.sav: Compression bias (0) is not the usual
value of 100.
The data appear to be OK, but I am concerned.
(I tried searching the archives and the documenation for data
2018 Sep 20
1
Bias in R's random integers?
> From: Duncan Murdoch <murdoch.duncan at gmail.com>
> Let's try it:
>
> > m <- (2/5)*2^32
> > m > 2^31
> [1] FALSE
> > x <- sample(m, 1000000, replace = TRUE)
> > table(x %% 2)
>
> 0 1
> 399850 600150
>
> Since m is an even number, the true proportions of evens and odds should
> be exactly 0.5.
2006 Jan 12
1
Firths bias correction for log-linear models
Dear R-Help List,
I'm trying to implement Firth's (1993) bias correction for log-linear models.
Firth (1993) states that such a correction can be implemented by supplementing
the data with a function of h_i, the diagonals from the hat matrix, but doesn't
provide further details. I can see that for a saturated log-linear model, h_i=1
for all i, hence one just adds 1/2 to each count,
2013 Nov 14
1
Re: make_random_password(): avoid modulo bias, and do not deplete system entropy (#9)
On Thu, Nov 14, 2013 at 01:48:17AM -0800, edwintorok wrote:
> Following the link to builder.ml from your blogpost I noticed the make_random_password () function, and I have some suggestions, well nitpicks really. See the 2 commits from this pull request.
>
> 1. Using Ocaml's buffered I/O means that one make_random_password() call reads 64k bytes from /dev/urandom which drops the
2007 May 09
1
Fitting model with response and day bias
Hi,
I'm trying to fit a model which has a response bias, but also a day to day
bias.
If I try to simulate the data, I don't get the right values with optim, and
also I can't
use the function to give a prediction interval.
My simulated data are:
DF <- as.data.frame(cbind(x=rep(1:10,2),dag=rep(1:2,each=10)))
bias <- c(-0.2,0.5)
DF$y <- ((DF$x-0.1) * 5)+2 +
2006 Jun 18
1
Method for selection bias with multinomial treatment
I have to the treatment effect base on the observational data.And the
treatment variable is multinomial rather than binary.Because the
treatment assignment is not random,so the selection-bias exists.Under
this condition,what's the best way to estimate the treatment effect?
I know that if the treatment is binary,I can use propensity score
matching using MatchIt package.But what about
2011 Sep 01
1
How to retrieve bias-corrected probability from calibrate.rms
Dear R users:
In Prof. Harrell's library rms, calibrate.rms plot the Bias-corrected
Probability and Apparent Probability.
The latter one can be retrieved from class calibrate.default. But how to
retrieve the former one.
BW
*Yao Zhu*
*Department of Urology
Fudan University Shanghai Cancer Center
Shanghai, China*
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2012 Mar 16
1
bias sampling
hi
i want to analyze Right Censore-Length bias data under cox model with covariate.
what is the package ?
tank you.
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