## Confuse-a-Cat [Two-Stage / GS Designs]

Hi again,

» Now I get it – though your code is beyond me. Zhang’s method in many cases hits the right point in the first attempt. Sometimes sampleN.TOST() has to iterate upwards (since Zhang’s method is based on a large sample approximation and power with anything of the t-family will be lower). In very rare cases sampleN.TOST() has to iterate downwards. Can your code do that as well?

Yes. Basically, get the initial initial guess, determine if it is low or high for the desired power, iterate up or down depending on that.

The reason I am doing this is I got a mental "Does not compute error" when I read Zhang's paper. The goal is to get to the right sample size in as few cycles as possible.

Pass or fail!
ElMaestro

21,316 posts in 4,446 threads, 1,489 registered users;
online 7 (0 registered, 7 guests [including 3 identified bots]).
Forum time: Wednesday 07:01 CET (Europe/Vienna)

Nothing fails like success because you do not learn anything from it.
The only thing we ever learn from is failure.
Success only confirms our superstitions.    Kenneth E. Boulding

The Bioequivalence and Bioavailability Forum is hosted by
Ing. Helmut Schütz