So the conclusion is that abline(0,1) should always be used and if it doesn't go through the qqplot, the two distributions are not similar?
Thanks --- On Mon, 11/2/09, Yihui Xie <xieyi...@gmail.com> wrote: > From: Yihui Xie <xieyi...@gmail.com> > Subject: Re: [R] qqplot > To: "carol white" <wht_...@yahoo.com> > Cc: "David Winsemius" <dwinsem...@comcast.net>, r-h...@stat.math.ethz.ch > Date: Monday, November 2, 2009, 8:42 AM > abline(0,1) is somewhere in the > upper-left corner which you are unable > to see. At least the first distribution seems to have a > larger mean > than the second one (i.e. they are not the same > distribution). > > Regards, > Yihui > -- > Yihui Xie <xieyi...@gmail.com> > Phone: 515-294-6609 Web: http://yihui.name > Department of Statistics, Iowa State University > 3211 Snedecor Hall, Ames, IA > > > > On Mon, Nov 2, 2009 at 10:33 AM, carol white <wht_...@yahoo.com> > wrote: > > if I have the two following matrices, abline(0,1) > doesn't go through. QQplot is attached. > > > > [,1] [,2] [,3] [,4] > [,5] > > 2.149644 1.992864 3.346375 2.793511 3.428230 > > 1.100762 2.152981 2.735401 2.175185 3.323058 > > 1.212406 2.131813 2.672598 2.389996 3.242490 > > 1.183770 1.908633 2.661237 2.590545 2.906059 > > 1.665190 1.778923 2.636062 2.475619 4.013407 > > > > > > 0.601 0.083 0.520 0.920 -0.007 > > -0.778 0.427 -0.605 -0.066 -0.283 > > -0.599 0.348 -0.693 0.284 -0.436 > > -0.519 0.081 -0.590 0.678 -1.095 > > 0.009 -0.253 -0.940 0.526 1.623 > > > > > > --- On Mon, 11/2/09, David Winsemius <dwinsem...@comcast.net> > wrote: > > > >> From: David Winsemius <dwinsem...@comcast.net> > >> Subject: Re: [R] qqplot > >> To: "carol white" <wht_...@yahoo.com> > >> Cc: r-h...@stat.math.ethz.ch > >> Date: Monday, November 2, 2009, 8:17 AM > >> > >> On Nov 2, 2009, at 10:40 AM, carol white wrote: > >> > >> > Hi, > >> > We could use qqplot to see how two > distributions are > >> different from each other. To show better how they > are > >> different (departs from the straight line), how is > it > >> possible to plot the straight line that goes > through them? I > >> am looking for some thing like qqline for qqnorm. > I thought > >> of abline but how to determine the slope and > intercept? > >> > >> I always assumed that the intercept was zero and > the slope > >> = unity. > >> > >> y <- rt(200, df = 5) > >> qqnorm(y); qqline(y, col = 2) > >> qqplot(y, rt(300, df = 5)) > >> abline(0, 1, col="red") > >> > >> I am open to education if that assumption is too > >> simplistic, but you have not offered anything in > the way of > >> a counter-example. > >> > >> > > >> == > >> > >> 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. > > > > > ______________________________________________ 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.
