Bioequivalence and Bioavailability Forum

Hi ElMaestro,

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❝ ❝ Say, you dosed N subjects and are interested in post hoc power of a fraction f of this sample size (e.g., of eligible subjects).

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❝ Accusing me of being a member of the post-hoc power fan club?

No accusation, of course. Amazingly it is still popular (in some countries…)

❝ I think my membership was discontinued around 2007.

❝ For me, pre-study power considerations led me to look into this. Like checking a range of prospective attrition rates to evaluate the actual power.

❝ Before, not after.

Kudos, good practice. ICH E9 Section 3.5 suggests a sensitivity analysis a priori to assess the impact on power depending on deviations from assumptions. See also this article for examples.

❝ […] an unfortunate habit in the industry is to adjust assumptions to make the sample size / power meet a target, not the other way around.

Well, the infamous Boss Button in FARTSSIE…

❝ So, I would not invest too much too much time on fixing this one. PowerTOST is a great tool and the matter here does not in any way detract from its value.

It’s an easy fix. We will do it.

❝ You and Detlew and possibly other people involved are doing a great job. Muchas gracias.

¡De nada!