[Limdep Nlogit List] hyper parameters a b in random effects negbin

William Greene wgreene at stern.nyu.edu
Thu Jul 1 07:16:36 EST 2010

Steven. I don't think that is true at all. They are the two parameters of some
underlying beta distribution, and so far as I know, do not have a direct
interpretation. You should check the 1984 Hausman, Hall and Griliches (Econometrica)
paper where that model was created for more details. For my money, the random
effects NB model should be created by having a random parameters NB model in which
the constant term is a random parameter. That puts it on the same platform as other
familiar random effects models.
Bill Greene

----- Original Message -----
From: "Steven Thornburg" <sthornburg at wsu.edu>
To: "Limdep and Nlogit Mailing List" <limdep at limdep.itls.usyd.edu.au>
Sent: Wednesday, June 30, 2010 5:12:37 PM GMT -05:00 US/Canada Eastern
Subject: [Limdep Nlogit List] hyper parameters a b in random effects negbin

Dr Greene
Is it safe to say that the hyper parameters in the random effects negative binomial model [a, b ] can be interpreted as [mean dispersion across groups, variance of dispersion across groups] ?

Steven Thornburg, Ph.D. CPA
Assistant Professor
Todd 237F
Department of Accounting
Washington State University
Pullman, WA 99164
Voice:  (509) 335-2222
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