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Re: st: Stata's functions relating to the binomial distribution


From   jlinhart@stata.com (Jean Marie Linhart, StataCorp LP)
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Stata's functions relating to the binomial distribution
Date   Thu, 04 Nov 2004 14:39:14 -0600

Joseph Coveney writes:

> But is there any way to improve accuracy in the following direction?
> Or is it that I'm not understanding these functions correctly?
>
> . display invbinomial(100, 50, Binomial(100, 50, 0.5))
> .50996594
> 
> . display invbinomial(100, 50, Binomial(100, 50, 0.999))
> .85115891

Please note the definition for invbinomial() -- it is a bit unusual:

from -help invbinomial-:

invbinomial(n,k,P) returns the inverse binomial: for P<=0.5, probability p
such that the probability of observing k or more successes in n trials is P;
for P>0.5, probability p such that the probability of observing k or fewer
successes in n trials is 1-P.

Hope that helps.

--Jean Marie 
jlinhart@stata.com
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