Re: [R] exact conditional mantelhaen.test estimate is 0 ?!

From: <f.hahne_at_dkfz-heidelberg.de>
Date: Sat 09 Jul 2005 - 20:11:51 EST

Thanks for the quick answer, that's what I was thinking too. Just wasn't sure wether this was a bug or a matter of computations becoming singular. Florian

> On Fri, 8 Jul 2005, Florian Hahne wrote:
>
> > Dear listers,
> >
> > I am trying to compute the exact conditional test given strata margins
> > of a 2 by 2 by K array using the mantelhaen.test function to get a
> > common odds ratio estimate.
> > The estimate for the test on the following data is 0, which in my
> > opinion dosen't make any sense.
> >
>
> Indeed it doesn't. Some probabilities are underflowing to zero. It is
> informative to look at the estimates from
> mantelhaen.test(round(x/s), exact=TRUE)
> for various values of s. The estimate is stable at about 0.04 for
> large s until s gets to just above 1.8, then quickly decreases to zero.
>
> I think you need exact=FALSE for data sets this large.
>
> -thomas
>



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