Date:         Thu, 23 Feb 2012 10:14:03 -0600
Reply-To:     Martha Hewett <mhewett@mncee.org>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Martha Hewett <mhewett@mncee.org>
Subject:      guidance on assigning cases to participant and control groups
Content-Type: multipart/alternative;

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
dimensions.

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?

Martha Hewett
Director of Research | 612.335.5865
Center for Energy and Environment
212 Third Avenue North, Suite 560 | Minneapolis, MN 55401
(cell) 612.839.2358 | (fax) 612.335.5888 | www.mncee.org

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