On Mar 11, 2008, at 8:26 AM, Feiveson, Alan H. (JSC-SK311) wrote:
Hi - I have been repeatedly asked by people who I convinced to buy
Stata how to do multiple comparisons of interaction effects under more
"complicated" anova models such as those with at least one factor
random
and possibly with repeated measures, etc. Apparently Stata does not
have
a built-in command/option for multiple comparisons for anything but a
one-way model and does not even support approximate methods for such
comparisons other than using xtmixed and creating all the contrasts
and
tests "by hand". Even then, further processing has to be undertaken to
account for multiple testing.
There are a couple Stata FAQs related to ANOVA testing:
http://www.stata.com/support/faqs/stat/#anova
From the number of helper programs written by Phil Ender and others
at ATS UCLA, there may be helpfulness in your advice to your colleagues!
http://www.ats.ucla.edu/stat/stata/topics/anova.htm
Side by side by side post hoc analysis of interactions from a mixed
ANOVA in Stata and SPSS and SAS and R would be enlightening.
Embarassingly enough, I have had to refer people to SAS to do these
types of comparisons without a lot of customized programing. Am I
missing something or is Stata really woefully deficient in this area?
Al Feiveson
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* http://www.ats.ucla.edu/stat/stata/
