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From | Maarten buis <maartenbuis@yahoo.co.uk> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: negative binomial model |
Date | Sun, 20 Jun 2010 17:03:41 +0000 (GMT) |
-------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- --- On Sun, 20/6/10, Mareike wrote: > I want to analyze count data. Given that for several > reasons the Poisson analysis showed to be inappropriate, > my idea was to run a negative binomial model(using the > command xtnbreg because I have panel data). But what > happened was that Stata was giving me one iteration after > the other (what appeared in the result window lokked like > the following: > Iteration 14721:log likelihood = -53.558237 (not > concave) > and after 3 hours and ten thousands of iterations I stopped > the program without having gotten any result. > Does anybody of you have an idea of what happened? I didn't > have the problem when running the Poisson model using the > same dataset. It means that the model is too complex for your data, so you need to simplify your model, either move back to -xtpoisson- or remove some explanatory variables. Hope this helps, Maarten * * 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/