qqplot
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 <xieyihui at 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_crl at 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 <dwinsemius at comcast.net> wrote:
From: David Winsemius <dwinsemius at comcast.net> Subject: Re: [R] qqplot To: "carol white" <wht_crl at yahoo.com> Cc: r-help at 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
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