Re: [R] fisher exact for > 2x2 table

From: viostorm <rob.schutt_at_gmail.com>
Date: Fri, 29 Apr 2011 08:43:53 -0700 (PDT)

After I shared comments form the forum yesterday with the biostatistician he indicated this:

"Fisher's exact test is the non-parametric analog for the Chi-square test for 2x2 comparisons. A version (or extension) of the Fisher's Exact test, known as the Freeman-Halton test applies to comparisons for tables greater than 2x2. SAS can calculate both statistics using the following instructions.

  proc freq; tables a * b / fisher;"

Do people here still stand by position fisher exact test can be used for RxC contingency tables ? Sorry to both you all so much it is just important for a paper I am writing and planning to submit soon. ( I have a 4x2 table but does not meet expected frequencies requirements for chi-squared.)

I guess people here have suggested R implements, the following, which unfortunately are unavailable at least easily at my library but at least by the titles indicates it is extending it to RxC

Mehta CR, Patel NR. A network algorithm for performing Fisher's exact test in r c contingency tables. Journal of the American Statistical Association 1983;78:427-34.  

Mehta CR, Patel NR. Algorithm 643: FEXACT: A FORTRAN subroutine for Fisher's exact test on unordered r x c contingency tables. ACM Transactions on Mathematical Software 1986;12:154-61.

The only reason I ask again is he is exceptionally clear on this point.

Thanks again,

-Rob

viostorm wrote:
>
> Thank you all very kindly for your help.
>
> -Rob
>
> --------------------------------
> Robert Schutt III, MD, MCS
> Resident - Department of Internal Medicine
> University of Virginia, Charlottesville, Virginia
>

viostorm wrote:
>
> Thank you all very kindly for your help.
>
> -Rob
>
> --------------------------------
> Robert Schutt III, MD, MCS
> Resident - Department of Internal Medicine
> University of Virginia, Charlottesville, Virginia
>

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