Hi everybody:

I'm frustrated and tired at the same time, therefore, I'm asking for help. I have Hilbe's "Negative Binomial Regression" besides me, and I'm trying to get negative binomial regression models with PASW/SPSS 18. Here are my questions:

1) How can I test for overdispersion in a Poisson Regression Model? Hilbe's book it's absolutely focused on Stata (including some software he actually wrote to easy the task). Hilbe mentions a Z test and a Lagrange multiplier test, and shows some Stata commands that let me absolutely non the wiser.

2) What role plays the scale (usually fixed at 1) factor in PASW 18 negative binomial regression output?. I have tried to use the "estimate it" option, but the output still shows its value fixed at 1. I don't see anything like that in Hilbe's book

Thanks (with a bit of migraine) Marta GG

-- For miscellaneous SPSS related statistical stuff, visit: http://gjyp.nl/marta/

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