[R] Fisher test problem
chainsawtiney at gmail.com
Sun Mar 22 03:07:29 CET 2009
I tried the OpenEpi, the p-value of 1.25 is due to the fact that the
one tailed p-value is 0.62. The two tailed p-value then is 0.62 * 2 =
1.25. OpenEpi is not clever enough to ceiling the p-value to 1.
On Sun, Mar 22, 2009 at 3:43 AM, David Winsemius <dwinsemius at comcast.net> wrote:
> Let me ask you: What degree of credibility should be accorded a WWW
> application that delivers a p-value of 1.25?
> If the answer is not immediately and glaringly obvious, then tell us, what
> sort of axioms of probability are you working with?
> 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
>> 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
>> R-help at r-project.org mailing list
>> PLEASE do read the posting guide
>> and provide commented, minimal, self-contained, reproducible code.
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Research Assistant - KWH
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