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Re: st: Re: pprob


From   Philip Ender <ender97@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Re: pprob
Date   Sat, 2 Oct 2010 08:23:46 -0700

Stephen Sullivan <stephen_sullivan@brown.edu> wrote:

Hello.
Could someone please provide some Stata advice with respect to "pprob"?
I have a dataset, which does not appear to fit the Poisson distribution.
I then ran glm and nbreg commands as suggested
(http://www.ats.ucla.edu/stat/stata/library/count.htm).
To see how the my variable fit the Poisson and negative binomial
distributions, I downloaded and used the nbvargr command.
Nevertheless, something seems strange as all pprob values for the Poisson are 0.
-------------------------------------
Stephan-

The mean value for your data is 47.92857 so the poisson probabilities
for small counts (0 to 11) is smaller than the number of decimal
places in the output.  The -nbvargr- program works best with
relatively small mean counts that are encountered in classroom data.
You can try increasing the n() option to 55 or you can subtract a
constant from each of the observations for graphing purposes.   Sorry
that you had problems with the program.

Phil
-- 
Phil Ender
UCLA Statistical Consulting Group
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