Date: Tue, 6 May 2008 10:30:24 -0700
Reply-To: Amy Smith <asmith197401@YAHOO.COM>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Amy Smith <asmith197401@YAHOO.COM>
Subject: Re: Is it true that a zero-inflated Gamma model is not possible
in either GENMOD or NLMIXED?
Content-Type: text/plain; charset=iso-8859-1
I'm trying to do a two-part model that is partly like a logistic regression on whether or not a person has costs and partly like a glm with link=log and dist=gamma if that person has costs. See my email below.
----- Original Message ----
From: Wensui Liu <liuwensui@GMAIL.COM>
To: SAS-L@LISTSERV.UGA.EDU
Sent: Tuesday, May 6, 2008 1:17:43 PM
Subject: Re: Is it true that a zero-inflated Gamma model is not possible in either GENMOD or NLMIXED?
do you know the probablity function of the model you wanted?
On 5/5/08, Amy Smith <asmith197401@yahoo.com> wrote:
> Has anyone found a procedure in SAS for creating a zero-inflated Gamma model? My response variable is cost. I have a class variable called group that has three levels Intervention1, Intervention2, and Control.
> The following two models succeed without any problem.
> PROC GENMOD;
> CLASS group;
> MODEL cost = group / LINK=log DIST = bin;
> PROC GENMOD;
> CLASS group;
> MODEL cost = group / LINK=log DIST = gamma;
> I cannot figure out how to get GENMOD to join these to give a zero-inflated gamma model. Or I thought maybe NLMixed could handle this model but I cannot get the syntax to work right and I'm now questioning if it is even possible. Has anyone ever written SAS code that successfully runs on a zero-inflated gamma? I would really love to see the syntax on a simple example like I have here.
> Thanks for your help!
>
>
>
> ____________________________________________________________________________________
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--
===============================
WenSui Liu
ChoicePoint Precision Marketing
Phone: 678-893-9457
Email : wensui.liu@choicepoint.com
Blog : statcompute.spaces.live.com
===============================
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Be a better friend, newshound, and
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