“Type 1” slightly higher power than “Type 2” for the same adj. α [Two-Stage / GS Designs]

posted by Helmut Homepage – Vienna, Austria, 2017-02-18 12:51 (2595 d 10:20 ago) – Posting: # 17081
Views: 13,463

Hi BE-proff,

I agree with ElMaestro.

❝ 2) Why Method C is considered "better" for sponsors than Method B?


Unfortunately there is an „inflation” of letters denoting methods.
Therefore, I suggested* to use “Type 1” (B, E, …) and “Type 2” (C, D, C/D, F, …) instead.

“Type 1”

[image]


“Type 2”

[image]


In “Type 2” TSDs the conventional (unadjusted) α 0.05 may be used in the first stage (dependent on interim power). Hence, under certain conditions you have a decent chance to stop already in the first stage with no sample size penalty (due to the mandatory adjusted α in “Type 1” TSDs).

Potvin et al. recommended Method C over B due to its higher power. Examples (power by the noncentral t-approximation):

n1 CV (%)   B      C   
12   10   0.97697 0.98858
24   20   0.88046 0.90882
36   30   0.83704 0.84676
48   40   0.82901 0.82838
60   50   0.82477 0.82405




Dif-tor heh smusma 🖖🏼 Довге життя Україна! [image]
Helmut Schütz
[image]

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

Complete thread:

UA Flag
Activity
 Admin contact
22,957 posts in 4,819 threads, 1,636 registered users;
69 visitors (0 registered, 69 guests [including 13 identified bots]).
Forum time: 23:11 CET (Europe/Vienna)

Nothing shows a lack of mathematical education more
than an overly precise calculation.    Carl Friedrich Gauß

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