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From | Maarten buis <maartenbuis@yahoo.co.uk> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Mixed Poisson models with degenerate conditional distribution for a given value of a covariate |
Date | Wed, 2 Mar 2011 08:30:39 +0000 (GMT) |
--- On Wed, 2/3/11, Alexander Limonov wrote: > I'm working with a count data-generating process where the > dependent variable is restricted to 0, if one of the > covariates (let's say it's nonnegative and discrete) is 0. > This occurs in a nontrivial number of cases. Otherwise, the > dependent variable may be assumed to follow any conditional > discrete distribution of your choice, but Poisson could be a > start. <snip> > -Does the ZIP model fit the process I'm describing, and > what modifications are necessary? > > -If yes, is there a way to "hack" this together with > existing Stata procedures? > > -If no, what model would be appropriate? Sounds to me similar to a selection model. The classic example would be the case where we are explaining women's income and homemakers have no income. -cmp- seems to allow for a wide range of selection models which could include count models. You can download that package by typing in Stata -ssc install cmp-, a paper explaining it can be found here: <http://ideas.repec.org/p/cgd/wpaper/168.html> Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/