Bioequivalence and Bioavailability Forum

Hi Helmut,

Should't we calculate stage-2 sample size with GMR of 0.95??

I am trying to understand if this will be helpful in case of drugs which are very highly variable e.g. Mesalamine.

Hypothetically, if study conducted with N=24, fully replicate design but T/R ratio observed worse like 0.72.

And if calculate power with reduced alfa in study using actual result of T/R=0.72, ISCV=0.6978 and N=24 using powerTOST package.

power.RSABE(alpha = 0.0294, theta0 = 0.72, CV = 0.6978, n = 24, design = "2x2x4")
[1] 0.18378 (which is less than 80%).

To recalculate the sample size with actual variability and assumed T/R of 95% and reduced alfa.

rss(n = 24, r = 2, S_WR = 0.630, params = list(sig_level=0.0294))
$rss
21

this N=21 is total sample size right?? not the additional sample size (plz correct me if i am wrong)

Since, we have already started study with N=24, we cant go ahead with stage-2.

Am i missing something?

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Edit: Subject line changed; see also this post #2. [Helmut]