🚀 go-pugleaf

In article <1992Aug22.214340.10028@ucsu.Colorado.EDU> mcclella@yertle.Colorado.EDU (Gary McClelland) writes:
>ted@dgbt.doc.ca (Ted Grusec) writes:
>
>>My CSS:Statistica (Statsoft) program will not analyze a 2 X 10 X 13
>>within-subject design. It indicates a 252 dependent variable limit,
>>while this experiment has 260.  All of this despite a recent update
>>to release 3.1 which I got just days ago,
>
>>Is there any commercial package that will do "large" within-subject
>>designs? Can someone share experiences, make recommendations?
>
>No sympathy from me.  With such large within-subject designs the key
>sphericity and homogeneity assumptions are almost surely violated.
>No one should be doing such large within-s analyses.  It is much better
>to think of the much smaller degree-of-freedom questions you really want
>to ask of your 260 data values for each subject.  Then, any standard
>regression program can be used to answer those specific questions.
>For details, see
>
>Judd, C.M., & McClelland, G.H. (1989).  Data Analysis: A Model Comparison
>   Approach.  HBJ  (see especially Chapter 14)
>
Thanks. But I should point out that, in real world applications of
experimental design, people sometimes want answers to explicit
questions that lead you into designs that, whether you like it or not,
result in violations of theoretical assumptions.  Also, some questions
are pressing - important decisions need to made and there are narrow
time limits.  All of this was true in my case.  Having done (and now,
thanks to |Stat having analyzed) the experiment, it only now is
obvious which levels of which factors proved uninformative. But there
is no time to rerun this extremely expensive experiment. For better or
worse, the decisions, based on the experiment, have been made.

For many years, I taught experimental design and stat. Having long
since left academia, I am sometimes tempted to offer a course which
would sprinkle some "real world" constraints into design applications.
It's something, I'm afraid, many academics are unaware of, as I too
was unconscious of when I was in that situation.

-- 
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Ted Grusec    Communications Research Centre    (Govt. of Canada, DOC)
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