[R] Fisher test problem

Viju Moses vijumoses at gmail.com
Sat Mar 21 20:17:41 CET 2009

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

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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