More: When the t-stat is > 0 should I use 'pt' differently?
I have been checking my results and (except for the example I posted) all the inconsistencies occur when t>0 Worik On Thu, Jun 17, 2010 at 10:30 AM, Worik R <wor...@gmail.com> wrote: > I have two pairs of related vectors > x1,y1 > > and > > x2,y2 > > I wish to do a test for differences in means of x1 and y1, ditto x2 and y2. > > I am getting odd results. I am not sure I am using 'pt' properly... > > I have not included the raw vectors as they are long. I am interested if I > am using R properly... > > > c(length(x1), length(y1), length(x2), length(y2)) > [1] 3436 1619 2677 2378 > > > First where the T-stat and the DF do not give the same result as 't.test' > when passed into 'pt' > > > t.1 <- t.test(x1, y1) > > 2 * pt(t.1$statistic, t.1$parameter) > t > 1.353946 > > t.1$p.value > [1] 0.646054 > > I would have thought these would have been the same. Like below.... > > > t.2 <- t.test(x2, y2) > > 2 * pt(t.2$statistic, t.2$parameter) > t > 0.8679732 > > t.2$p.value > [1] 0.8679732 > > This is what I expect. > > clearly I misunderstand some thing. What is it? > > cheers > Worik > [[alternative HTML version deleted]] ______________________________________________ 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.