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st: Zero Inflated Poisson


From   "francesca.modena" <francesca.modena@email.unitn.it>
To   statalist@hsphsun2.harvard.edu
Subject   st: Zero Inflated Poisson
Date   Fri, 14 Dec 2007 10:46:09 +0100

Dear all,

I run a zero inflated poisson model. The sample is 409 observations, with 87
nonzero observations and 322 zero observations. There are 42 independent
variables. Long and Freese (2001) report a general rule of at least 10
observations per parameter for models for categorical dependent variables,
but they suggest that the zero-inflated poisson model seems to require more
observations.

Moreover, if there is little variation in the dependent variable (as could
be this case, in which nearly all of the outcomes are 0), a larger sample is
required. 

Can you suggest me if 42 parameters are too many for my sample?

Thanks 
Francesca  




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