# Bioequivalence and Bioavailability Forum 07:36 CET

## Power.TOST and "3x3" [R for BE/BA]

Dear all,
or perhaps mainly the powerTOST authors and maintainers

thanks a lot for power.TOST and related functions. They are great.

I have a question about e.g.

```> power.TOST(CV=.3, theta0=.95, n=30, design="3x3") [1] 0.6973262```

Is that the chance of showing BE for one of the comparisons, for two comparisons if we assume two are tests formulations and one if ref, or is it "all against all" which is also a common comparison?

Now, I am asking because theta0 seems to be a single number, not a vector.
Imagine we have formulations A, B and C; if true ratios for A/B and B/C are 0.95 then in my little simple universe the true ratio for A/C is ~0.9. Therefore, I imagine it is not for all against all (3 comparisons in my case).

So I wonder what goes on behind the curtains in R when I give the command above and how I should interpret the output here. I read the documentation and did not see an obvious answer but I am also not so well versed with power.TOST.

Many thanks for any input.
Or output, depending on your perspective.

` if (3) 4 `

Best regards,
ElMaestro

"(...) targeted cancer therapies will benefit fewer than 2 percent of the cancer patients they’re aimed at. That reality is often lost on consumers, who are being fed a steady diet of winning anecdotes about miracle cures." New York Times (ed.), June 9, 2018.