In addition to being confused about many things, I got out of bed far too early for a Saturday ;) I see I misunderstood the question, and it certainly doesn't hurt to go back to text books now and again...
> x<-cbind(rnorm(1000),rnorm(1000),rnorm(1000)) > m<-rowMeans(x) > s<-apply(x,1,sd) > qqnorm(m/(s*sqrt(3))) Cheers, T. On Sat, Oct 26, 2013 at 10:26 AM, Rolf Turner <r.tur...@auckland.ac.nz>wrote: > On 10/26/13 21:20, Tsjerk Wassenaar wrote: > > Of course. But the point is that this would happen with summing samples > from any distribution. > > > ***What*** would happen? You are confused about the t-distribution. (And > the CLT and probably > a lot of other things.) Back to the text-books. > > cheers, > > Rolf Turner > > > Cheers, > > Tsjerk > > > On Sat, Oct 26, 2013 at 10:14 AM, Rolf Turner <r.tur...@auckland.ac.nz>wrote: > >> >> >> Absolutely nothing to do with the CLT. If X_1, ..., X_n are i.i.d. N(mu, >> sigma^2) then >> Xbar is N(mu,sigma^2/n). Exactly. No asymptotics, no approximations, no >> CLT. >> >> cheers, >> >> Rolf Turner >> >> >> On 10/26/13 20:17, Tsjerk Wassenaar wrote: >> >> Hi :) >> >> Try this with other distributions too... And then search for 'central limit >> theorem'. >> >> Cheers, >> >> Tsjerk >> >> >> On Fri, Oct 25, 2013 at 4:48 PM, Kramer, Christian >> <christian.kra...@uibk.ac.at> wrote: >> >> >> Hi there, >> >> I have found a strange behavior in R that puzzles me - maybe it is a bug >> or a basic scientific misunderstanding of mineââ¬Â¦ anyway, I would highly >> appreciate some feedback on this, since I did not find anything on the >> internet. >> >> I am trying to simulate a t-distribution by adding up normally distributed >> numbers: >> >> a <- (rnorm(1000) + rnorm(1000) + rnorm(1000) )/3 >> >> However, when I look at the distribution using >> >> qqnorm(a) >> >> this looks more like a normal distribution than a t-distribution: >> >> b <- rt(1000,2) >> qqnorm(b) >> >> Is this to be expected? Or is this an issue with the random number >> generator or something else? >> >> Thanks a lot for replies in advance, >> Christian >> >> -------------------------------------------- >> Dr. Christian Kramer >> Theoretical Chemistry >> University of Innsbruck >> Innrain 82 >> A-6020 Innsbruck >> Tel.: +43 512 507 57103 >> >> Homepage: http://homepage.uibk.ac.at/~c72448/kramer.html >> Email: christian.kra...@uibk.ac.at >> >> ______________________________________________r-h...@r-project.org mailing >> listhttps://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> >> >> >> >> ______________________________________________r-h...@r-project.org mailing >> listhttps://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. >> >> >> > > > -- > Tsjerk A. Wassenaar, Ph.D. > > > -- Tsjerk A. Wassenaar, Ph.D. [[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.
