On Sat, 21 Mar 2009 markle...@verizon.net wrote: > by definition, the one tailed p-value has to be <= 0.5 so there is still > something wrong with your OpenEpi calc.
I think that's a little strong. Firstly, a one-tailed test in a pre-determined direction can have any p-value. Secondly, even the smaller one-sided tail probability can be >0.5. The problem is discreteness. It may be that 0.62 is the smaller of p(T>=t) and p(T<=t), and this turns out to be the case. The other tail probability is 0.83. OpenEpi should still be thresholding the p-value at 1, but that's just cosmetic. -thomas Thomas Lumley Assoc. Professor, Biostatistics tlum...@u.washington.edu University of Washington, Seattle ______________________________________________ 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.