[R-sig-ME] Design question about repeated measures as nested vscrossed structures

Doran, Harold HDoran at air.org
Tue Oct 6 21:47:32 CEST 2009


We have a description of what this means in the paper in the link below.
See section 1.6 of the paper. Using your example below, whether or not
the multiple observations are nested would depend on the setting in
which they were observed. For instance, if all students had two scores
and both of those scores were observed in one and only one classroom,
you would have a nested design. 

If some students had one of those scores observed with teacher i and
another observed with teacher i', then your design would be partially

If every student had one observation observed in one class and the
second observation in a different class, you would have a fully crossed



> -----Original Message-----
> From: r-sig-mixed-models-bounces at r-project.org 
> [mailto:r-sig-mixed-models-bounces at r-project.org] On Behalf 
> Of Ista Zahn
> Sent: Tuesday, October 06, 2009 3:35 PM
> To: r-sig-mixed-models at r-project.org
> Subject: [R-sig-ME] Design question about repeated measures 
> as nested vscrossed structures
> Sorry for the off-topic post, I've been struggling to 
> understand something and don't know where else to turn. I 
> don't understand the distinction between nested and cross 
> classified, and I'd really appreciate if someone can take a 
> moment to set me straight. The example below illustrates my confusion.
> I often read/hear multivariate measures data described as 
> nested, but this doesn't make sense to me. Here is a typical 
> explanation from
> http://www.cmm.bris.ac.uk/lemma/mod/lesson/view.php?id=255:
> "Sometimes we may wish to model more than one response. For 
> example, we may wish to consider jointly English and 
> mathematics exam scores for students because the two 
> responses are likely to be related. We can regard this as a 
> multilevel structure with subjects (English and
> maths) nested within students as shown in Figure 4.5. ..." 
> (the figure is here: 
> http://www.cmm.bris.ac.uk/lemma/file.php/13/images-C4/image007.gif).
> To my mind this sounds cross-classified, because each 
> observation is a particular combination of person and exam 
> subject. It seems to make just as much sense to describe 
> these data as participant nested within exam subject, as I've 
> diagrammed here:
> http://ista.scp.rochester.edu/snapshot1.png.
> Please, if anyone can clear this up for me I'd really appreciate it.
> -Ista
> --
> Ista Zahn
> Graduate student
> University of Rochester
> Department of Clinical and Social Psychology http://yourpsyche.org
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