Re: [R] Help with Beta Distribution

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From: A.J. Rossini (rossini@blindglobe.net)
Date: Thu 24 Jan 2002 - 05:07:13 EST 

Message-id: <87vgdt3pri.fsf@jeeves.blindglobe.net>

>>>>> "TR" == Tharacad Ramanarayanan <Tharacad.Ramanarayanan@aventis.com> writes:

    TR> First let me confess that I am a R-novice. I am trying to fit
    TR> a beta distribution for a dataset using fitdistr(MASS). I am
    TR> having difficulties with it because the function tends to fit
    TR> a distribution with a range of 0 to 1 (I guess). However, my
    TR> dataset is not!

    TR> Since a beta (range in 0,1) doesn't describe what you want,
    TR> why force it?

    TR> Hmm . . . a standard beta distribution(B(x)) is 0 < x < 1. So
    TR> is a standard uniform distribution. A standard beta
    TR> distribution can be transformed for any (positive) range.

Right - so did you transform your data back (or rewrite the
distribution forward)?

It does work when everything is on the same scale.

best,
-tony 

-- 
A.J. Rossini				Rsrch. Asst. Prof. of Biostatistics
U. of Washington Biostatistics		rossini@u.washington.edu	
FHCRC/SCHARP/HIV Vaccine Trials Net	rossini@scharp.org
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