R help - Jun 2002 - problem with boot

Hello R-users,

I'm using the boot's library. I have two questions:

1. I execute for example

                    data<-rnorm(100)
                    boot(data,mean,500)

and I obtain 500 equal bootstrap samples of data. Why?


2. I need to calculate the bootstrap confidence intervals for a statistic,
but when I use the function boot.ci it shows the error message:

       Error in if (!all(rk > 1 & rk < R)) warning("Extreme Order
Statistics
used as Endpoi...

What is happening?

Thank you,

Juan

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On Wed, 19 Jun 2002, Juan Ramon Gonzalez wrote:
> Hello R-users,
>
> I'm using the boot's library. I have two questions:
>
> 1. I execute for example
>
>                     data<-rnorm(100)
>                     boot(data,mean,500)
>
> and I obtain 500 equal bootstrap samples of data. Why?
Because you haven't read the help page or studied the examples. See the
description of `statistic' in ?boot.

Please consult the Davison & Hinkley book for more details.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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See the "statistics" argument in help file for boot. I guess what you
want is

Data <- rnorm(100)
foo <- function(d, i) mean(d[i])
boot(data = Data, statistic = foo, R = 500, stype = "i")

The second problem comes from a diseased distribution for the stat of
interest. It might be cured with an appropriate syntax for the boot
call.

Best,

Renaud

Juan Ramon Gonzalez wrote:
> 
> Hello R-users,
> 
> I'm using the boot's library. I have two questions:
> 
> 1. I execute for example
> 
>                     data<-rnorm(100)
>                     boot(data,mean,500)
> 
> and I obtain 500 equal bootstrap samples of data. Why?
> 
> 2. I need to calculate the bootstrap confidence intervals for a statistic,
> but when I use the function boot.ci it shows the error message:
> 
>        Error in if (!all(rk > 1 & rk < R)) warning("Extreme
Order Statistics
> used as Endpoi...
> 
> What is happening?
> 
> Thank you,
> 
> Juan
> 
>
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> r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
> Send "info", "help", or "[un]subscribe"
> (in the "body", not the subject !)  To: r-help-request at
stat.math.ethz.ch
>
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-- 
Dr Renaud Lancelot, v?t?rinaire
CIRAD, D?partement Elevage et M?decine V?t?rinaire (CIRAD-Emvt)
Programme Productions Animales
http://www.cirad.fr/presentation/programmes/prod-ani.shtml

ISRA-LNERV                      tel    (221) 832 49 02
BP 2057 Dakar-Hann              fax    (221) 821 18 79 (CIRAD)
Senegal                         e-mail renaud.lancelot at cirad.fr
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