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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: RE: Hypergeometric Distribution |

Date |
Wed, 22 Aug 2007 19:16:30 +0100 |

There are many answers to this, but dinner supervenes. If you push hard enough, and show why it is needed, either StataCorp or a user will write a program for this. The evidence since 1999 has been that such a program is not needed. Nick n.j.cox@durham.ac.uk Marcello Pagano > Why buy Stata if you are expected to do all this for yourself? > Nick Cox wrote: > > Apply -ln()-, -exp()- and -cond()- as needed. > > > > Nick > > n.j.cox@durham.ac.uk > > > > Marcello Pagano > > > > > >> Just concerned with the accuracy. > >> > > > > > >> Nick Cox wrote: > >> > > > > > >>> Roger's posting includes what I presume is an allusion to > >>> an -egen- function _ghyper.ado that I wrote in 1999. > >>> > >>> I withdrew this program as redundant some years ago, > >>> given that you can use something like > >>> > >>> comb(K, k) * comb(N - K, n - k) / comb(N, n) > >>> > >>> wherever you want. In context N, K, n, k may be > >>> variables, scalars or placeholders for numeric > >>> constants, or any mixture thereof. > >>> > >>> This might need a wrapper to yield zeros where > >>> appropriate, or it might need care whenever > >>> individual terms get very large, but otherwise > >>> does it raise any problems? > >>> > >>> Nick > >>> n.j.cox@durham.ac.uk > >>> > >>> Marcello Pagano > >>> > >>> > >>> > >>>> I looked at --ssizebi-- but it seems to be focused on power > >>>> and sample > >>>> sizes. > >>>> > >>>> > >>> > >>> Newson, Roger B wrote: > >>> > >>> > >>> > >>>>> Thanks to Marcello for telling us all about this > >>>>> > >> recently-published > >> > >>>>> algorithm, which looks very useful. A search on > >>>>> > >>>>> findit hypergeometric > >>>>> > >>>>> in Stata finds a single reference (to a SSC package), which was > >>>>> distributed as long ago as 1999. This suggests that the new > >>>>> > >>>>> > >>>> algorithm > >>>> > >>>> > >>>>> might be a good candidate for implementation in Mata by > >>>>> > >>>>> > >>>> Marcello, or by > >>>> > >>>> > >>>>> anybody else with the time and inclination to do so. > >>>>> > >>>>> > >>> Marcello Pagano > >>> > >>> > >>> > >>>> Does anyone have or know of Stata code to calculate the > >>>> > >> Hypergeometric > >> > >>>> Distribution accurately? > >>>> > >>>> See Journal of Discrete Algorithms , Volume 5 , Issue 2 > >>>> > >> (June 2007) > >> > >>>> Pages: 341-347 for an article by Berkopec, HyperQuick > >>>> > >> algorithm for > >> > >>>> discrete hypergeometric distribution > >>>> > >>>> > > <http://portal.acm.org/citation.cfm?id=1240586&coll=GUIDE&dl=GUIDE&CFID= > >>> 27443384&CFTOKEN=80678482>. >>> * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: RE: Hypergeometric Distribution***From:*Marcello Pagano <pagano@hsph.harvard.edu>

**References**:**Re: st: RE: Hypergeometric Distribution***From:*Marcello Pagano <pagano@hsph.harvard.edu>

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