Date:         Tue, 16 Aug 2011 02:58:36 -0700
Reply-To:     Steve Denham <stevedrd@yahoo.com>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Steve Denham <stevedrd@YAHOO.COM>
Subject:      Re: user-defined link function in GLIMMIX
Comments: To: Andrew <wacox@MIZZOU.EDU>
In-Reply-To:  <201108152024.p7FI0Qo2001530@waikiki.cc.uga.edu>
Content-Type: text/plain; charset=iso-8859-1

The GLIMMIX documentation includes a section on "User Defined Link or Variance Function" that gives a good start.  Note that _LINP_ must NOT appear on the left side of the equal sign.
 
Assuming the notation in the documentation, you could try (easy part):
a=1/x;
_MU_=((exp(_LINP_)/(1+exp(_LINP_))**(1/a);
 
The hard part for me is defining _VARIANCE_ in terms of _LINP_, but if you can do that, this should all fall into place. When invoking the model statement, no DIST= or LINK= option would be given.
 
Good luck.

Steve Denham
Associate Director, Biostatistics
MPI Research, Inc.

From: Andrew <wacox@MIZZOU.EDU>
>To: SAS-L@LISTSERV.UGA.EDU
>Sent: Monday, August 15, 2011 4:24 PM
>Subject: user-defined link function in GLIMMIX
>
>I am unclear on how to correctly program a user-defined link function in GLIMMIX.  The link function
>is very similar to the logit link and looks like this:
>
>log((mu**a)/(1-mu**a)) where a= 1/x
>
>It seems like it should be fairly straightforward, but not for me.  Any help is much appreciated!
>
>Andrew Cox
>University of Missouri - Columbia
>
>
>