[R] Simulating from the null distribution of a 2 x 3 table

[peter dalgaard]

On Jul 7, 2011, at 05:01 , Thomas Lumley wrote:

> On Thu, Jul 7, 2011 at 12:58 PM, Jim Silverton <jim.silverton at 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
> 
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-- 
Peter Dalgaard
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
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Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com