Thanks for all your help thus far. My final question is this, if I want to
simulate all the 2 x 3 tables (with column totals and row totals fixed), how
do I do this  using r2dtable(), and find the one that gives me the smallest
fisher's exact test.
Will r2table() generate unique tables everytime to a certain point and is
there a function which can give the unique tables?

Jim

On Thu, Jul 7, 2011 at 4:29 AM, peter dalgaard <pdalgd@gmail.com> wrote:

>
> On Jul 7, 2011, at 05:01 , Thomas Lumley wrote:
>
> > On Thu, Jul 7, 2011 at 12:58 PM, Jim Silverton <jim.silverton@gmail.com>
> wrote:
> >> Dear all,
> >>
> >> I want to simulate from the null distribution of the following 2 x 3
> table,
> >>
> >> 2   5  10
> >> 4   8   5
> >>
> >> I am using  a chi-squared test.
> >> Anyone has any idea how to do this?
> >
> > The r2dtable() function will simulate tables with a given set of row
> > and column totals.
>
> Or, as a shortcut, maybe look into chisq.test(..., simulate.p.value=TRUE).
>
> Notice that both use hypergeometric-type sampling. One could also consider
> sampling with rmultinom (either of order 6, twice of order three, or thrice
> of order 2), or even rpois, assuming a Poisson distribution of the total
> count.
>
>
> >
> >    -thomas
> >
> > --
> > Thomas Lumley
> > Professor of Biostatistics
> > University of Auckland
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> --
> Peter Dalgaard
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Email: pd.mes@cbs.dk  Priv: PDalgd@gmail.com
>
>


-- 
Thanks,
Jim.

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