[SciPy-user] looking for a negative binomial distribution

Chris Fonnesbeck listservs@mac....
Sat Aug 23 04:25:05 CDT 2008


Chris Fonnesbeck <listservs <at> mac.com> writes:
> Robert Kern <robert.kern <at> gmail.com> writes:
> > Fixed in numpy SVN. This will be part of the upcoming 1.2.0 release
> > and probably 1.1.2 if we do one.
> > 
> 
> Thanks Robert,
> 
> I would have poked around the source code myself, but I'm on a deadline. I will
> update and test the code now though.
> 
> The easiest way to generate NB random variables is to sample from a gamma, 
> then use that value as the mean for a sample from a poisson.
> 

The fix appears to work, though the samples appear to be biased high relative to 
thosegenerated using another method, based on a couple tests. I'll make sure 
I'm not making an error first, before complaining again. The first parameter does
accept non-integer arguments now, however.

Thanks,
cf






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