David Winsemius
On Mar 21, 2009, at 3:17 PM, Viju Moses wrote:
> Hi, I noted a discrepancy between R and openepi when I ran a fisher
> test with the same matrix. In R:
>
> > a=matrix(c(1,2,6,17), nrow=2)
> > a
> [,1] [,2]
> [1,] 1 6
> [2,] 2 17
> > fisher.test(a, conf.int=T)
>
> Fisher's Exact Test for Count Data
>
> data: a
> p-value = 1
> alternative hypothesis: true odds ratio is not equal to 1
> 95 percent confidence interval:
> 0.02061498 31.73691924
> sample estimates:
> odds ratio
> 1.396646
>
> But in openepi the P value is 1.25. (In another instance too for
> other sets of data, I had got a p value of 1 in 3 instances for a
> prop.test when I got 3 other answers on a friend's stata software
> with the same data. )
>
> I'm using R on Ubuntu Intrepid. Is there anything I'm doing wrong?
> Any other packages I have to install?
>
> Thanks in advance
>
> Viju Moses
>
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT