[R] FW: [Fwd: Re: [S] Exact p-values]

[Christian.Stratowa@vie.boehringer-ingelheim.com]

Dear all

Just for fun, I have just downloaded the paper mentioned below and checked
it with R-1.6.1.
Everything is ok with exception of Table 2b, where I get always 1 instead of
0.5:
> pbinom(1e15,2e15,0.5)
[1] 1

Which value should be correct?

Best regards
Christian Stratowa

==============================================
Christian Stratowa, PhD
Boehringer Ingelheim Austria
Dept NCE Lead Discovery - Bioinformatics
Dr. Boehringergasse 5-11
A-1121 Vienna, Austria
Tel.: ++43-1-80105-2470
Fax: ++43-1-80105-2683
email: christian.stratowa at vie.boehringer-ingelheim.com


> -------- Original Message --------
> Subject: Re: [S] Exact p-values
> Date: Thu, 13 Feb 2003 18:31:38 +0100
> From: "Rau, Roland" <Rau at demogr.mpg.de>
> To: 'Spencer Graves' <spencer.graves at PDF.COM>,	Jose María Fedriani
> Laffitte <fedriani at ebd.csic.es>
> CC: s-news at lists.biostat.wustl.edu
> 
> Dear all,
> 
> in relation to your question, the following working paper of Leo Knuesel,
> University of Munich, might be of interest:
> "On the Accuracy of Statistical Distributions in S-Plus for Windows
> (1999)"
> You can download the paper from (pdf-Format, 45k):
> http://www.stat.uni-muenchen.de/~knuesel/elv/accuracy.html
> 
> Best,
> Roland
> 
>  > -----Original Message-----
>  > From:	Spencer Graves [SMTP:spencer.graves at PDF.COM]
>  > Sent:	Thursday, February 13, 2003 6:12 PM
>  > To:	Jose María Fedriani Laffitte
>  > Cc:	s-news at lists.biostat.wustl.edu
>  > Subject:	Re: [S] Exact p-values
>  >
>  >
>  > Try ( 1-pchisq(29.8, df=1)):  With S-Plus 6.1, I got  4.78992e-008.
>  >
>  >          By the way, the distribtion functions in R have more
> arguments.
>  >  For example,  pchisq(29.8, df=1, lower.tail=F) produces the same
>  > answer, and pchisq(29.8, df=1, lower.tail=F, log=T) produces its
> natural
>  > logarithm.  Also, pchisq, dchisq, qchisq, and rchisq in R all have an
>  > "ncp" noncentrality parameter argument;  only pchisq has such in S-Plus
>  > 6.1.  Similarly, none of the Student's t functions in S-Plus have a
>  > non-centralitity parameter;  in R, pt has an argument ncp, and from
> this
>  > one can easily program ncp for dt, qt and rt.  Also, the distribution
>  > functions in the current release of S-Plus are known to have problems.
>  >  For example, pt(-1, Inf) = 0.5 in S-Plus 6.1, but 0.159 in R;
> clearly,
>  > S-Plus gives a wrong answer without warning.
>  >
>  > Best Wishes,
>  > Spencer Graves
>  >
>  > Jose María Fedriani Laffitte wrote:
>  >
>  > >Dear all,
>  > >
>  > >    I want to get the exact p-values, on 1 degree of freedom, for an
>  > array
>  > >of chi-square values.  When my chi-square values are equal or lower
> than
>  > >29.7, I get the exact associated p-values.  Thus, for instance:
>  > >
>  > >
>  > >
>  > >>pchisq(29.7, df=1)
>  > >>
>  > >>
>  > >[1] 0.9999999
>  > >
>  > >However, when my chi-square values are greater or equal to 29.8 what I
>  > get
>  > >is:
>  > >
>  > >
>  > >
>  > >>pchisq(29.8, df=1)
>  > >>
>  > >>
>  > >[1] 1
>  > >
>  > >
>  > >    Could anyone tell me how to fix this trivial issue?  Very
> grateful,
>  > Jose
>  > >M. Fedriani
>  > >
>  > >****************************************
>  > >Jose Mª Fedriani Laffitte
>  > >Estacion Biologica de Donana (CSIC)
>  > >Avda. Mª Luisa s/n
>  > >41013-Sevilla
>  > >Spain
>  > >Tel. +34-954232340
>  > >Fax +34-954621125
>  > >http://ebd.csic.es
>  > >
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