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.
CH On Sun, Mar 22, 2009 at 3:43 AM, David Winsemius <dwinsem...@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 >> 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 >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > David Winsemius, MD > Heritage Laboratories > West Hartford, CT > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- CH Chan Research Assistant - KWH http://www.macgrass.com ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.