On Wed, 17 Sep 2008, Peter Dalgaard wrote:
fisher.test(...., simulate.p.value=TRUE)  might be more direct. Also
works for chisq.test().

And, contrary to popular belief,  fisher.test() does work for larger
than2x2 tables, although you may run into space/time limitations.

The 'exact' test computations do suffer from roundoff error if your tables are too large. I think we saw a 3x11 table that had problems.

It would be nice to see if the original Mehta & Patel algorithm TOMS 643 is more accurate, but I haven't been able to find code: it seems to have been replaced everywhere by the faster Clarkson et al code.

        -thomas

Thomas Lumley                   Assoc. Professor, Biostatistics
[EMAIL PROTECTED]       University of Washington, Seattle

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