[R] Confidence Intervals from Bootstrap Replications

Ashraf Chaudhary mchaudha at jhsph.edu
Mon Dec 20 00:54:50 CET 2004

Thank you for the response. The suggestions are helpful. I would look into
the capabilities of the boot function. The solution in 8.3 is the last
resort that I was trying to avoid. Regards,

-----Original Message-----
From: Berton Gunter [mailto:gunter.berton at gene.com] 
Sent: Friday, December 17, 2004 5:54 PM
To: 'Mohammad A. Chaudhary'; r-help at stat.math.ethz.ch
Subject: RE: [R] Confidence Intervals from Bootstrap Replications 

See , e.g. section 8.3 "The two-sample problem" of Efron and Tibshirani's AN
INTRODUCTION TO THE BOOTSTRAP. It makes it clear there why one just
bootstrap samples independently from the two separate samples.

The "strata" argument of boot() in the boot package allows one to do such
independent sampling and use the capabilities of that function.

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> Mohammad A. Chaudhary
> Sent: Friday, December 17, 2004 2:39 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Confidence Intervals from Bootstrap Replications 
> Hi All:
> I have to compute bootstrap confidence intervals, the statistic
> (incremental cost effectiveness ratio) is computed from two samples
> (intervention and control) of different sizes. All the bootstrap
> functions that I have seen use one dataset as argument. I may go ahead
> and get the desired number of bootstrap replications 
> separately. I would
> appreciate if you could point me to a source of a bootstrap 
> function (if
> available) that takes the B bootstrap replications and other 
> descriptive
> statistics and can get me the confidence intervals. Please 
> write me if I
> have not been clear in explaining my problem. Regards,
> Ashraf  
> ___________________________________
> M. Ashraf Chaudhary, Ph.D.
> Associate Scientist/Biostatistician
> Department of International Health
> Disease Prevention and Control Program
> Johns Hopkins University Bloomberg School of Public Health
> 615 North Wolfe Street, Room W5506
> Baltimore MD 21205
> mchaudha at jhsph.edu 
> Phone: (410) 502-0741/Fax: (410) 502-6733
> http://faculty.jhsph.edu/?F=Mohammad&L=Chaudhary
> 	[[alternative HTML version deleted]]
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