Date:         Tue, 6 May 2008 13:17:43 -0400
Reply-To:     Wensui Liu <liuwensui@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Wensui Liu <liuwensui@GMAIL.COM>
Subject:      Re: Is it true that a zero-inflated Gamma model is not possible
              in either GENMOD or NLMIXED?
Comments: To: Amy Smith <asmith197401@yahoo.com>
In-Reply-To:  <686409.96586.qm@web45813.mail.sp1.yahoo.com>
Content-Type: text/plain; charset=ISO-8859-1

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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