Date: Thu, 23 Feb 2012 11:35:24 -0500
Reply-To: Gene Maguin <email@example.com>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: Gene Maguin <firstname.lastname@example.org>
Subject: Re: guidance on assigning cases to participant and control groups
Maybe I'm not understanding something but why have you rejected random
assignment of owners to condition?
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
Sent: Thursday, February 23, 2012 11:14 AM
Subject: guidance on assigning cases to participant and control groups
I'm involved with a project that is recruiting 100 to 200 owners of
multifamily properties, with 1 to 10 properties each (average 5), for an
energy efficiency project. Because the project's effectiveness depends in
significant part on influencing the owners, we need to assign all of any
given owner's properties to either participant or control status. Beyond
the owners, however, there are many property-specific factors that may
affect savings, such as the age of the buildings, number of units, type of
heating equipment, etc. Obviously there will not be enough owners or
properties to match the participant and control groups on all of these
So my question is, when you have a large number of more or less independent
(but possibly somewhat correlated) dimensions that may affect outcomes
relative to the size of your sample, what is the best way to assign cases to
participant or control status? What additional considerations are
introduced by the fact that I have to assign participant/control status by
owner but need to consider other factors by property?
If someone can point me to a suitable methodology, I'm sure I can figure out
how to apply it.
And yes, I agree, wouldn't it be great if n could be bigger?
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