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 -- View this message in context: http://www.nabble.com/Fisher-test-accuracy-in-doubt-tp22639239p22639239.html Sent from the R help mailing list archive at Nabble.com.
On Sat, Mar 21, 2009 at 2:03 PM, joker77 <vijumoses at gmail.com> 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. )Given that a p-value is between 0 and 1, I would rather think that openEpi's accuracy is in doubt. Hadley -- http://had.co.nz/