Re: st: RE: Re: How to implement Incomplete Beta Function in Stata?

[Pablo Mitnik <pmitnik@ssc.wisc.edu>]

Thanks much, Alan, for your answer.
Based on what the manual says (Stata 9, D-161), it seems to me ibeta 
generates  the incomplete beta function divided by the beta function, 
what sometimes is called the regularized incomplete beta function.You 
can see there that the incomplete beta function (Integral[t^(a-1) * 
(1-t)^(b-1) dt, 0, x] ) appears multiplied by the reciprocal of the Beta 
function (Gamma(a+b)/Gamma(a) + Gamma(b)). So you would need to multiply 
by the Beta function to get the incomplete Beta function.
Pablo


Feiveson, Alan H. (JSC-SK311) wrote:

> no - it's just -ibeta- it gives a value between 0 and 1
>
> AL F. 
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Pablo Mitnik
> Sent: Wednesday, January 02, 2008 11:22 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: Re: How to implement Incomplete Beta Function in Stata?
>
> I think I found it. It seems it can be implemented as ibeta( ) * beta (
> ), where beta is implemented using exp and lngamma.
>
> pmitnik@ssc.wisc.edu wrote:
>   
> > Dear all,
> >
> > Does anyone know how to implement the incomplete Beta function in 
> > Stata? I am not referring to the Beta function, which can be 
> > implemented using lngamma. A  description of the function I need to 
> > use is in Mathematica's Web site, at 
> > http://mathworld.wolfram.com/IncompleteBetaFunction.html. I am hoping 
> > there is an indirect way of implementing it using existing functions,
> >     
> which I have missed.
>   
> > All best,
> >
> > Pablo Mitnik
> >   
> >     
> --
> Pablo A. Mitnik
> University of Wisconsin-Madison (http://www.wisc.edu/ ) Department of
> Sociology ( http://www.ssc.wisc.edu/soc/) Center on Wisconsin Strategy
> (http://www.cows.org/ ) 1180 Observatory Drive Room 7114A Madison, WI
> 53706 TEL (608) 2621839
> E-mail: pmitnik@ssc.wisc.edu 
>
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--
Pablo A. Mitnik
University of Wisconsin-Madison (http://www.wisc.edu/ )
Department of Sociology ( http://www.ssc.wisc.edu/soc/)
Center on Wisconsin Strategy (http://www.cows.org/ )
1180 Observatory Drive
Room 7114A
Madison, WI 53706
TEL (608) 2621839
E-mail: pmitnik@ssc.wisc.edu 

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