[R] Getting all possible contingency tables

[Christofer Bogaso]

Thanks Bert for your reply.

I am trying to understand/visualize the Sample Chi-Squared Statistic's 
Null distribution. Therefore I need all possible Contingency tables 
under Independence case.

What could be better way to visualize that?

Thanks and regards,

On 01 December 2012 20:03:00, Bert Gunter wrote:
> Christopher:
>
> Don't do this!
>
>  If I understand you correctly, you want FIsher's exact test. This is
> already available in R, using far smarter algorithms then you would. See:
>
> ?fisher.test
>
> -- Bert
>
> On Sat, Dec 1, 2012 at 5:48 AM, Christofer Bogaso
> <bogaso.christofer at gmail.com <mailto:bogaso.christofer at gmail.com>> wrote:
>
>     Thanks John for your reply. However still not clear how I should
>     proceed.
>
>     My goal is to generate all possible contingency tables. Basically
>     I want to see the distribution of Chi-squared Statistic under
>     independence (NULL).
>
>     So I was thinking if I can generate all possible permutation of
>     integer numbers having sum equal to (8 + 10 + 12 + 6) = 36. Is
>     there any R function to do that?
>
>     Thanks and regards,
>
>
>     On 01-12-2012 18:39, John Kane wrote:
>
>         Are you basically asking for all possible permutations of the
>         table?  If so see ?permn in the combinat package.
>
>         John Kane
>         Kingston ON Canada
>
>
>             -----Original Message-----
>             From: bogaso.christofer at gmail.com
>             <mailto:bogaso.christofer at gmail.com>
>             Sent: Sat, 01 Dec 2012 18:10:15 +0545
>             To: r-help at r-project.org <mailto:r-help at r-project.org>
>             Subject: [R] Getting all possible contingency tables
>
>             Hello all,
>
>             Let say I have 2-way contingency table:
>
>             Tab <- matrix(c(8, 10, 12, 6), nr = 2)
>
>             and the Chi-squared test could not reject the independence:
>
>               > chisq.test(Tab)
>
>                       Pearson's Chi-squared test with Yates'
>             continuity correction
>
>             data:  Tab
>             X-squared = 1.0125, df = 1, p-value = 0.3143
>
>
>             However I want to get all possible contingency tables
>             under this
>             independence scenario (one of them would obviously be the
>             given table
>             as, we could not reject the independence), and for each
>             such table I
>             want to calculate the Ch-sq statistic.
>
>             Can somebody help me how to generate all such tables?
>
>             Thanks and regards,
>
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>
>
> --
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
> Internal Contact Info:
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