[R] Sample all possible contingency tables both margin fixed

[peter dalgaard]

On 24 Jun 2014, at 16:41 , Tahira Jamil <tahjamil at gmail.com> wrote:

> Hi,
> 
> I am interested in generating all possible contingency table (2 by 2) with fixed row margins and column margins. Can anyone help me. 
> 


It's pretty easy, just find one compatible solution and add or subtract

1 -1
-1  1

until one of the numbers would go negative. Or put differently, if you know one entry, you know the other three, so it is just a matter of working out the range of (say) possible top-left entries.

With more than 2x2 tables it is much harder, but fisher.test() does it internally.

-pd


> Best regards,
> Tahira 
> 	[[alternative HTML version deleted]]
> 
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-- 
Peter Dalgaard, Professor,
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