type known.designs() in PowerTOST [Study As­sess­ment]

posted by Helmut Homepage – Vienna, Austria, 2019-02-20 15:14  – Posting: # 19941
Views: 3,689

Hi Rosy,

» But in this case: https://accp1.onlinelibrary.wiley.com/doi/abs/10.1177/009127009903901108?sid=nlm%3Apubmed
»
» The study had an open-label, single-dose, three-way crossover design. Subjects were randomly assigned to receive one of three treatments per period

Was it a Latin Square (ABC|BCA|CAB) or a Williams’s design (ABC|ACB|BAC|BCA|CAB|CBA)? Not mentioned anywhere in the paper. But this part is strange:

Seventeen healthy [:blahblah:] were enrolled.

Enrolled, how comes? It is OK to have dropouts but to start a study with incomplete sequences is bizarre. The sample size has to be a multiple of the number of sequences.

» A vs B ----> IC (84.9-106)
» A vs C ----> IC (169-211)
» B vs C ----> IC (178-222)
»
» 100*CVfromCI(lower=0.849, upper=1.06, n=17, design='2x2x3', alpha=0.05)
» it's that correct???

No, it isn’t. "2x2x3" is for the two-treatment two-sequence three-period full replicate design (TRT|RTR).
For the Latin Square use "3x3" and for the Williams’ design "3x6x3". BTW, in all functions of PowerTOST the default is alpha=0.05. As long as you deal with the 100(1–2×0.05) = 90% confidence interval you can simply leave it out. ;-)

Cheers,
Helmut Schütz
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