Re: [Rd] phyper returns 1 if x==k (PR#8499)

From: <ripley_at_stats.ox.ac.uk>
Date: Wed 18 Jan 2006 - 10:01:24 GMT


On Wed, 18 Jan 2006 utz.pape@molgen.mpg.de wrote:

> Full_Name: Utz J. Pape
> Version: 2.2.0
> OS: linux
> Submission from: (NULL) (141.14.23.12)
>
>
> If I use phyper and set parameter x equal to k (meaning that all balls I draw
> are white) phyper returns 1 which is not (always) correct:

I think you are confusing this with dhyper. How can you possibly get more white balls than exist in the urn? That you cannot is what p = 1 is telling you.

We do quite specifically ask you not to report on obselete versions of R. Of course, as this is NOT A BUG, it is the same in the current R.

>
> pape@xxx:~> R2.2.0 --vanilla
>
> R : Copyright 2005, The R Foundation for Statistical Computing
> Version 2.2.0 (2005-10-06 r35749)
> ISBN 3-900051-07-0
>
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>> x <- 10; m <- 20; n <- 5; k <- 10
>> phyper(x,m,n,k)
> [1] 1
>> choose(m,x) * choose(n,k-x) / choose(m+n,k)
> [1] 0.05652174
>> version
> _
> platform i686-pc-linux-gnu
> arch i686
> os linux-gnu
> system i686, linux-gnu
> status
> major 2
> minor 2.0
> year 2005
> month 10
> day 06
> svn rev 35749
> language R
>> sessionInfo()
> R version 2.2.0, 2005-10-06, i686-pc-linux-gnu
>
> attached base packages:
> [1] "methods" "stats" "graphics" "grDevices" "utils" "datasets"
> [7] "base"
>
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-- 
Brian D. Ripley,                  ripley@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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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Received on Wed Jan 18 21:06:41 2006

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