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st: powercalculation for four-sample trial with repeated measures


From   "Maren Kandulla" <m.kandulla@uke.uni-hamburg.de>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: powercalculation for four-sample trial with repeated measures
Date   Thu, 23 Jun 2005 09:04:29 +0200

Hello Stata-users,
My name is Maren from Hamburg. I am doing an evaluation about different
curricula in medical education. I have four different treatment groups
(students) to compare and longitudinal data for 7 different measuring times.
Since we have small sample size I would like to calculate the power for our
tests.
Does anybody know how to calculate power (or samplesize) for a four-sample
comparison with repeated measures?
I found that:

sampsi mean1 mean2, sd1() sd2() method(change) pre(x) Post(y) r1(z) n1()
n2()

works for two-sample comparison with repeated measures but not for a
four-sample trial.
The ADOs: simpower and ssizebi are brilliant for a four-sample comparison,
but do not offer a method for repeated measures.

If anybody solved this problem before, I would be glad for help.

Best regards,
Maren


*****************************************************************
Maren Kandulla
Wissenschaftliche Mitarbeiterin / Evaluation
Modellstudiengang Medizin
Universitätsklinikum Hamburg-Eppendorf


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