Hi John:
I don't have Maddala's (1977) textbook, but I have his monograph on LDVs,
and he touches briefly upon count data models in it, yet he does not
mention the negative binomial model. He merely says that count data models
are to be used (I'm paraphrasing) "when the outcome is discrete but not
categorical, e.g. 0, 1, 2, 3, ..." I don't have my Cameron and Trivedi
(1986) book on count data with me, but you would be sure to find a
definitve answer in there.
Marc
At 04:41 PM 10/13/2004 -0700, you wrote:
In my earlier email, I meant to say "not" exceed 50 counts. There are a
lot of criminologists using these models with counts over 50 now, so if
this is true, it would be helpful to get the correct information
out. Alternatively, people may incorrectly be avoiding using these models
in sociology because of this reference.
Thanks,
John
> -----Original Message-----
> From: MacDonald, John
> Sent: Wednesday, October 13, 2004 4:23 PM
> To: '[email protected]'
> Subject: Negative Binomial Models
>
> Is there a maximum number of counts one should not exceed when using
the negative binomial model? Even if there is a adjustment for exposure
(e.g., rate of homicides in a city). I have a data set with over 200
homicides in some cities and I saw a reference in an article of American
Journal of Sociology to Maddala's 1977 econometrics textbook that said
you should exceed 50 counts. Is this true?
>
>
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__________
Marc F. Bellemare
Ph.D. Candidate
Department of Applied Economics and Management
Cornell University
Ithaca, NY 14853-7801
http://www.people.cornell.edu/pages/mfb24
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