Full ACK [Power / Sample Size]

posted by d_labes  – Berlin, Germany, 2017-12-28 18:41 (2450 d 10:19 ago) – Posting: # 18116
Views: 34,216

Dear David,

❝ In this case, given your simulations above and the expected probability of approximately 12% of the studies having power greater then 95% having in consideration the initial assumptions, post hoc power means nothing.


Full ACK.
But not only in this case, also in other cases. The concept of post-hoc power is flawed by its own.

❝ But if you had 100 studies instead and 90% of the had >95% power although the sample size was calculated assuming expected power of 80%, some questions and conclusions might be drawn from those results, don't you think? From my understanding of the initial question, this was the case found. So I think that they should start by reviewing how they define their assumptions for the sample size, namely why they assume GMR=1.10 instead of the "normal" 0.95/1.05.


Again: Full ACK.
—
Regards,

Detlew

Complete thread:

UA Flag
Activity
 Admin contact
23,223 posts in 4,877 threads, 1,655 registered users;
26 visitors (0 registered, 26 guests [including 4 identified bots]).
Forum time: 06:01 CEST (Europe/Vienna)

One of the symptoms of an approaching nervous breakdown
is the belief that one’s work is terribly important.    Bertrand Russell

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