Power limbo [Power / Sample Size]

posted by Helmut Homepage – Vienna, Austria, 2021-02-19 13:37 (218 d 18:44 ago) – Posting: # 22216
Views: 1,065

Hi ElMaestro,

» Yes to 0.53.

Shit, expected that.

» The risk is up to you or your client.

Such a case is not uncommon. Say, you have single dose studies (highest strength, fasting/fed), multiple dose studies with two strengths (fasting/fed). Then you get the n = 6 of my example.
If you want a certain overall power, then each study has to be powered to \(p_i=\sqrt[n]{p_\textrm{overall}}\).
With n = 6, for 80% → 96.35% and for 90% → 98.26%. Will an IEC accept that?*

» I think there is no general awareness, but my real worry is the type I error, as I have indicated elsewhere.

I know. ;-)

» Related issue, the one that worries me more:
» You test one formulation, it fails on the 90% CI, you develop a new formulation, it passes on the 90% CI. What is the type I error?

I’m not concerned about a new formulation. The first one went to the waste bin → zero consumer risk. The study supporting the new formulation stands on its own. Hence, TIE ≤0.05.

» Well, strictly speaking that would be inflated. But noone seems to give a damn. :-D

I’m indeed concerned about repeating the study (same formulation) with more subjects. Then you get an inflated TIE.

We have that everywhere. A value in the post-study exam is clinically significant out of range. Follow-up initiated and now all is good. Did the value really improve? There is always inaccuracy involved. Maybe the first one was correct and the second one not.

My doctor gave me six months to live,
but when I couldn’t pay the bill
he gave me six months more.
    Walter Matthau




Dif-tor heh smusma 🖖
Helmut Schütz
[image]

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

Complete thread:

Activity
 Admin contact
21,700 posts in 4,538 threads, 1,542 registered users;
online 5 (0 registered, 5 guests [including 4 identified bots]).
Forum time: Sunday 09:21 CEST (Europe/Vienna)

A central lesson of science is that to understand complex issues
(or even simple ones), we must try to free our minds of dogma and
to guarantee the freedom to publish, to contradict, and to experiment.
Arguments from authority are unacceptable.    Carl Sagan

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5