You asked for a stratified bootstrap, not a stratified estimator. This is
explained in the reference (Davison & Hinkley).
On Wed, 4 May 2005, Richard Chandler wrote:
Hello,
I am new to R, and am having trouble getting the output I want from a
stratified bootstrap. I didn't recieve a reply the first time I posted
this question so I have tried to make it more clear. My data frame
(denboot) is set up as follows:
SITE cswa parea treat
1 BeanA 3 1.20 m
2 BeanBC 3 1.05 m
3 BeanD 1 0.93 m
4 BlackB 1 1.01 m
5 Brooks 3 4.00 b
6 BullL 3 1.32 b
7 BullM 1 0.20 m
8 BullU 4 2.06 b
...
#Here is my code:
cswafun <- function(denboot, i) sum(cswa[i])/(sum(parea[i])
attach(denboot)
cswa.boot <- boot(denboot, cswafun, R = 10000, strata = treat)
#Here is the output
Call:
boot(data = denboot, statistic = cswafun, R = 10000, strata = treat)
Bootstrap Statistics :
original bias std. error
t1* 1.109612 0.02641786 0.2032927
#Can anyone tell me why I'm not getting two estimates of
sum(cswa)/sum(parea), one for each #strata ('b' and 'm')? Any help
would be appreciated. Thanks
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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