Selection of w and w* [Two-Stage / GS Designs]

posted by Helmut Homepage – Vienna, Austria, 2018-04-26 09:51 (838 d 01:48 ago) – Posting: # 18733
Views: 9,362

Dear Detlew,

» Defining the weights that way is IMHO not what you intended.

OK, I see!

» BTW: Choosing the weights "optimal" is for me a mystery. To do that, we had to know the outcomes of the two stages, but we don't have them until the study has been done. On the other hand we have to predefine them to gain strict TIE control. Hier beißt sich die Katze in den Schwanz.

Using the median of n.tot to define the weights from the sim’s was a – maybe too naïve – attempt. Other suggestions? Some regulatory statisticians prefer the first stage in a TSD to be like in a fixed sample design. For some combinations of n1/CV in my grid this will be ≤ the median of n.tot. In other words, I’m not too optimistic but rather too pessimistic. Now what?
Example: CV 0.1, GMR 0.95, target power 0.80. Fixed sample design’s n 8 (n1 ⇒ 12 acc. to GLs). n.mean and median of n.tot 12 with the default weights (0.5, 0.25). Even the 95% percentile of n.tot is 12.
:confused:

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
20,998 posts in 4,378 threads, 1,460 registered users;
online 66 (1 registered, 65 guests [including 16 identified bots]).
Forum time: Tuesday 11:39 CEST (Europe/Vienna)

Average a left-hander with a right-hander
and what do you get?    Donald Norman

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