Date: Wed, 15 Sep 2010 16:34:17 -0400
Reply-To: Art@DrKendall.org
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: Art Kendall <Art@DrKendall.org>
Organization: Social Research Consultants
Subject: Re: Generalized Estimating Equations (Clustering)
In-Reply-To: <201009152016.o8FAniBU024064@malibu.cc.uga.edu>
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I am up on design of experiments but not on the GEE procedure (i.e.,
with a dichotomous DV).
Perhaps someone else is more familiar with GEE.
BTW I see this as repeated measures. I am familiar with "clustering" in
the context of cluster analyses (pattern detection) and in the context
of clusters of cases in complex samples, but may be missing something in
the subject of the OP. Do GEE people use "clustering" to refer to
repeated measures, i.e., the same measurement method on the same
case/dyad under different conditions (doses, times, member of a dyad,
litter mates, etc.)
Also please explicate what you mean about the twins being more
correlated rather than the measurements o the twins being more
correlated? or were you just using shorthand?
Also if you are trying to tease out heredity vs environment the
difference between the adjusted correlations for measurements within
each kind of win would be an important aspect.
Art Kendall
On 9/15/2010 4:16 PM, Simon - slmartys@gmail.com wrote:
> Hmmm, I hadn't thought much about the MZ-DZ distinction because I was so
> concerned with the other questions. My guess is that it wouldn't matter
> for this, but if I wanted to account for it, would I add it as another IV
> factor...?
>
> There is the problem that MZ twins are more correlated than DZ twins, so
> we would guess that their residuals will be as well. Using the
> exchangeable covariance matrix will provide the most rigorous correction
> for clustering, correct? I'm bamboozled why someone told me independent
> correlation matrix...he said it was "completely counterintuitive" but the
> correct option.
>
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