Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: Count data problems

From   Claire <[email protected]>
To   <[email protected]>
Subject   st: Count data problems
Date   Tue, 20 Aug 2002 09:01:00 +0100


I have a large database of count data, 95% zeros & overdispersion (variance
25 x larger than the mean) - I have tried poisson, nbreg, zinb & zip with
the Vuong test.  The problem is that the results for the zinb, which the
Vuong test shows is preferable over the nbreg, are poor in that very few
explanatory variables are significant.  Is there any other way to account
for excess zeros/overdispersion using nbreg rather than zinb?  The reason I
can't accept my current nbreg model is that the scaled deviance is 1 but the
pearson deviance is 212 - I assume that this is not acceptable?



*   For searches and help try:

© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index