HI,
I didn';t get back to you because I thought your problem was solved .
Now I'm not so sure from what you wrote. Anyway my software is
not a solution to your problem, but it enables one to quickly code such a
solution and produce a stand alone estimation procedure or
if desitred a DLL which can be linked to SPLUS and becomes part of your
SPLUS package as it were. If you have a concise mathemtaical
description of your problem I cna code it up for you.
Dave
-----Original Message-----
From: Melanie Wigg <mbwigg@navigator.math.uwaterloo.ca>
To: s-news@wubios.wustl.edu <s-news@wubios.wustl.edu>
Date: Wednesday, February 24, 1999 8:17 AM
Subject: [S] Summary: Dirichlet-multinomial mixture
>
>Splus users,
>
>I recently posted the following question:
>
>>I am looking for an Splus function which would estimate the parameters
>>of a dirichlet-multinomial mixture (the multicategory analogue of
>>the beta-binomial). I also need this function to handle "counts" that
>>are not integers.
>>
>>Does anyone know of such an S-plus function?
>
>
>
>I received the following responses from ....
>
>Dean Billheimer
>----------------
>
>I don't have an S-plus function that directly estimates the
>Dirichlet-multinomial parameters. Several years ago I wrote some Splus
>code to perform this feat, and I don't think there was too much involved
>(I'm afraid the code fell by the way-side.) Mosimann (1962, I think)
>published a paper in Biometrika that provides expressions for the maximum
>likelihood estimators for the parameters. These can be solved numerically
>with nlmin() or nlminb(). As I recall, the only (relatively) tricky part
>was to re-parameterize so that the minizer uses only positive values for
>the parameter estimates (like exp(x)). (This may have been before
>nlminb() was available.)
>
>
>Thomas Yee
>-----------
>
>I think my VGAM software (http://www.stat.auckland.ac.nz/yee/vgam)
>should be able to handle it, provided somebody writes a family function
>for it.
>
>
>Dave Fournier also replied that he has some software that could do the job.
>-------------
>
>
>Thanks for these responses!
>Melanie Wigg
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