Date: Tue, 6 May 2008 10:13:16 -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 now going to offer a $15 gift card for Amazon.com to the first person that can give me functional NLMixed or GENMOD code that allows me to do the two part model that I am trying to do here. I'm looking for one p-value here. Yes, I'm officially that frustrated with NLMixed. My gift card offer expires at 5PM Eastern time on May 7, 2008.
A
----- Forwarded Message ----
From: Amy Smith <asmith197401@yahoo.com>
To: SAS-L@LISTSERV.UGA.EDU
Sent: Monday, May 5, 2008 5:52:43 PM
Subject: Is it true that a zero-inflated Gamma model is not possible in either GENMOD or NLMIXED?
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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