Re: st: "testing" a cluster analysis

["Adam Seth Litwin" <aslitwin@hotmail.com>]

This was all great advice.  Thank you very much.

You are all correct in that I wanted a way I could eyeball the data for 
theory-driven "clusters."  So, I built the 128-cell table using the 
-contract- command.  (Use of the zero option meant I did not need the 
-fillin- command.)  This is exactly what I needed.


> From: Steven Samuels <ssamuels@albany.edu>
> Reply-To: statalist@hsphsun2.harvard.edu
> To: statalist@hsphsun2.harvard.edu
> Subject: Re: st: "testing" a cluster analysis
> Date: Wed, 7 Feb 2007 11:31:05 -0500
>
> I agree with Nick's point about the distinct outcomes.  I would list  all 
> combinations of 2, 3, 4 ,5, 6, & 7 variables (start with 7). This  is 
> easily done after -contract- and -fillin-.  Changing the order of  the 
> variables in the list might be revealing. This approach will also  show you 
> associations: what responses almost always or almost never  appear 
> together. Validation of any "clusters" that you detect would  require that 
> you set aside a validation sample.
>
> Latent class analysis is another approach that might be considered.
>
> Steve
>
> On Feb 7, 2007, at 9:59 AM, Nick Cox wrote:
>
> I think Ron�n and Ken made excellent points.
>
> I am also queasy about this for quite a different
> reason. As I understand it, you have a discrete
> outcome space with 2^7 = 128 distinct outcomes.
> I am not clear that this lends itself to cluster
> analysis, nor would calculating means be what springs
> to my mind as natural.
>
> In principle, you lose no information by tabulating the
> frequencies of those 128 composite outcomes and sorting
> the table.
>
>
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