Lower bound for power of two combined TOST? [Power / Sample Size]

posted by d_labes  – Berlin, Germany, 2018-07-25 16:46 (2182 d 11:46 ago) – Posting: # 19100
Views: 5,309

Dear ElMaestro,

❝ ❝

Power >= PAUC + PCmax - (2 - 1)

where PAUC is the estimate of power for AUC and PCmax is the estimate of power for Cmax.


❝ Surely that's either wrong or an approximation that has some validity within a set of strict conditions. I have not read that work or reference 918, but it looks outright wrong.


Here we are two.
You may read under the link

https://books.google.de/books?id=e3byCOxj8FoC&pg=PA45

some more sparse details. Unfortunately the Appendix D with a proof of that formula is not available in Gooooogle books.

❝ With that equation power could become negative, go figure.


One nitpicking: The lower bound of power could become negative if both powers are <0.5, values no one would use in estimating sample sizes. If such a bound is reasonable is of course highly questionable.

Regards,

Detlew

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