Date:         Thu, 18 Sep 2008 22:08:54 -0700
Reply-To:     stringplayer_2@yahoo.com
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Dale McLerran <stringplayer_2@YAHOO.COM>
Subject:      Re: Logistic, Genmod, and Repeated Measures
In-Reply-To:  <1115a2b00809182025n491c885bna0a89007ff0eb863@mail.gmail.com>
Content-Type: text/plain; charset=us-ascii

Well, subject looks like a random effect.  Whether to use GLIMMIX
or GENMOD (or NLMIXED!) has more to do with whether a marginal
interpretation is desired or whether a conditional interpretation
is desired.  That is, do we want to make statements about average
effects in a population or about effects that might be observed
for an individual in some population.

If you want a population average interpretation, then you want
to use GENMOD.  If you want a subject-specific interpretation,
then you want to fit a random effects model.

Dale

---------------------------------------
Dale McLerran
Fred Hutchinson Cancer Research Center
mailto: dmclerra@NO_SPAMfhcrc.org
Ph:  (206) 667-2926
Fax: (206) 667-5977
---------------------------------------


--- On Thu, 9/18/08, Wensui Liu <liuwensui@GMAIL.COM> wrote:

> From: Wensui Liu <liuwensui@GMAIL.COM>
> Subject: Re: Logistic, Genmod, and Repeated Measures
> To: SAS-L@LISTSERV.UGA.EDU
> Date: Thursday, September 18, 2008, 8:25 PM
> peter,
>
> i have to disagree with you and see no point to use
> glimmix. where is the
> random effectin bruce's model?
>
> On Thu, Sep 18, 2008 at 1:28 PM, Peter Flom <
> peterflomconsulting@mindspring.com> wrote:
>
> > "Bruce A." <coreklenelim@YAHOO.COM>
> wrote
> > >
> > >I'm trying to analyze a dataset with repeated
> observations on the same
> > >subject with a dependent variable which is
> dichotomous.  So I used PROC
> > >GENMOD with the repeated statement.  However, when
> I compare that to the
> > >output when I use PROC LOGISTIC (which ignores
> dependency) I get the same
> > >estimates, the same confidence intervals of those
> estimates, and therefore
> > >I get the same p-hat values.
> > >
> > >Shouldn't I get different answers?  Am I using
> PROC GENMOD wrong?  Am I
> > >going crazy?
> > >
> > >These are the two codes I used:
> > >
> >
> > Not sure about your genmod code, but I think you
> should be using PROC
> > GLIMMIX
> >
> > Peter
> >
> > Peter L. Flom, PhD
> > Statistical Consultant
> > www DOT peterflom DOT com
> >
>
>
>
> --
> ===============================
> WenSui Liu
> Acquisition Risk, Chase
> Email : wensui.x.liu@chase.com
> Blog : statcompute.spaces.live.com
> ===============================