Precision of PowerTOST [Power / Sample Size]

posted by Helmut Homepage – Vienna, Austria, 2017-12-09 18:00 (2007 d 20:44 ago) – Posting: # 18049
Views: 13,317

Hi mittyri,

❝ I tried to figure out the precision of PowerTOST estimations with the following code:

  scABELdata$power[j] <- power.scABEL(CV=0.8, n=54, theta0=0.95,

                                      design="2x3x3", nsims=10000,


❝ please correct if it is wrong.

I think so.
You got the right answer to a wrong question. For theta0=0.95 and targetpower=0.8 sample sizes are 57 for design="2x3x3" and 56 for design="2x2x3". Therefore, with 54 power will be <0.8 for both designs:

power.scABEL(CV=0.8, theta0=0.95, n=57, design="2x3x3")
# [1] 0.82231
power.scABEL(CV=0.8, theta0=0.95, n=54, design="2x3x3")
# [1] 0.79917
power.scABEL(CV=0.8, theta0=0.95, n=56, design="2x2x3")
# [1] 0.81545
power.scABEL(CV=0.8, theta0=0.95, n=54, design="2x2x3")
# [1] 0.79883

❝ […] I would say that sample mean 80% in PowerTOST is a real unfortune :cool:

On the contrary; fortunately works as designed with the right sample sizes. :-D

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