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re: st: power repeated measures anova vs mixed models


From   "Airey, David C" <david.airey@vanderbilt.edu>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   re: st: power repeated measures anova vs mixed models
Date   Thu, 24 May 2012 10:01:26 -0500

.

I just came across this software for longitudinal / hierarchical experimental design power analysis:

http://sitemaker.umich.edu/group-based/optimal_design_software

I've not used it, but it might help you avoid simulation.

-Dave

> Dear all,
> 
> I have been struggling to find an answer or reference to this problem.
> 
> I am planning a longitudinal analysis comparing 3 groups with 6 time points per subject. The design is balance with 65 subjects for group. 
> 
> Because I do not have preliminary data and do not want to make unrealistic assumptions about the covariate structure and other parameters required to calculate power for mixed models, I decided to use repeated measures ANOVA to estimate the minimum detectable effect size at 80% power. 
> My questions are, will the mixed model have more power that the repeated measures ANOVA in this case? Are there any references regarding these comparisons?
> 
> Thank you,
> Ricardo
> 
> Ricardo Ovaldia, MS
> Statistician 
> Oklahoma City, OK


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