Answer: qqplot: theoretical Quantiles
Thanks for your explanation.
I understood qqnorm function in such a way:
The theoretical quantiles is computed by standard normal distribution.
x = ? + zσ (and/ or: z = x- mean/SD)
Is also the other theoretical distributions (e.g. F-Distribution or
t-Distribution) in R used?
> -----Urspr?ngliche Nachricht-----
> Von: Naomi Altman <naomi at="" stat.psu.edu="">
> Gesendet: 22.10.06 04:24:24
> An: Mohammad Esad-Djou <shahrgol at="" web.de="">
> Betreff: Re: [BioC] qqplot: theoretical Quantiles
> In theory, the idea is that if
> y1 ... yn are i.i.d. F, we sort them into
> y(1)<y(2)< ..<y(n)="" and="" plot="" these="" against="" the="" expected="" value="" of="" the=""> smallest, 2nd smallest, etc from a sample of size n generated from
> Taking such an expectation is difficult, so usually an approximation
> is given based on the quantiles of the proposed distribution:
> F(1/(n+1)), F(2/(n+1) ) ... F(n/(n+1))
> I have not looked at the R documentation to see the exact
> approximation used, but you can probably find it if you dig a bit.
> At 01:10 PM 10/21/2006, you wrote:
> >I use qqplot and would like to know, how theoretical quantiles is
> >Is there source about it?
> >Mohammad Esad-Djou
> >IZBI- Uni-Leipzig
> >Bioconductor mailing list
> >Bioconductor at stat.math.ethz.ch
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> Naomi S. Altman 814-865-3791 (voice)
> Associate Professor
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