Bioequivalence and Bioavailability Forum

Dear Detlew,

❝ The impact is also relevant if you don't think extremes.

I fully agree with you that the loss of power due to multiplicity should not be neglected, even in less extreme scenarios.
What I meant is that, in a usual (i.e. not too extreme) BE context, the absolute price (€ or $) to pay is not that high.

❝ We have to plan for a power of 90% to assure overall power around 80%, which gives n=26, a 30% increase. Not so small IMHO.

According to my calculation (SAS Proc Power), 24 subjects would be enough:
"single" power = 89.7% => "combined" power = 81.9%.
Moreover, just to nuance the impact of double testing on the sample size: in the design of a classical single-product BE study, increasing from 20 to 24 subjects would correspond to consider a CV of 23% instead of 20%.