st: re: RM ANOVA, was SPSS vs. Stata

["Airey, David C" <david.airey@Vanderbilt.Edu>]

.

> What SPSS still maintains over Stata is better ANOVA routines,
> particularly Repeated-Measures fixed-factor designs.  Stata treats RM
> designs a bit strangely, I believe because it seems to "wrap" ANOVA code
> around Regression methods.  It's non-intuitive and can provide results
> that aren't typical of RM ANOVA (consider how it uses full-n for
> fixed-factor RM ANOVA without listwise elimination of subjects who are
> missing an observation).  I would much prefer to see Stata invest in
> re-working their ANOVA code and analyses so that it is more consistant
> with SAS or SPSS methodologies, offers more in terms of assumption
> testing (ex. Sphericity tests), and is more intuitive.

Michael Mitchell pointed this out in his head to head to head comparison of Stata, SPSS, and SAS some years ago in a report posted at ATS UCLA.

I don't know if this is true anymore with version 11.1 of xtmixed and the margins functionality. This book shows use of xtmixed in designed experiments:

<http://www-personal.umich.edu/~bwest/almmussp.html>

BTW, you can test sphericity in Stata directly with the mvtest command or by asking for the univariate rm-anova corrections when you use the "repeated(varlist)" option to anova.

Doesn't SPSS wrap GLM for its RM-ANOVA routines?

Can you post an example of what you are talking about, re listwise elimination? I don't have SPSS.



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