Mea culpa! [Power / Sample Size]

posted by Helmut Homepage – Vienna, Austria, 2020-05-04 14:40 (1476 d 20:03 ago) – Posting: # 21395
Views: 8,288

Hi ElMaestro,

❝ the powerTOST package is excellent …


THX!

❝ … and I am not myself a very experienced user (yet) as I tend to rely on much less reliable code of my own making :-D


Sure. In line what Jaime once stated:

Never trust in any piece of software you haven't written yourself
(and even then you should be cautious…)


❝ So forgive me I am asking: I think the OP implied a partial replicate. TRR/RRT/RTR is not 3x6x3 but rather 2(trts)x3(seqs)x3(pers), …


Oops! You are absolutely right.

❝ ❝ 3 way crossover, reference replicate


❝ … is there a reason to plug in 3x6x3 in your code?


I screwed up! Of course, not a 3-period Williams’ design. Hence,

library(PowerTOST)
round(100 * CVfromCI(lower = 0.9625, upper = 1.2511,
                     n = 41, design = "2x3x3"), 2)

and

Unbalanced 2x3x3 design. n(i)= 14/14/13 assumed.
[1] 42.97

That’s reasonably close to the 42.6% given in the PAR. Sorry for the confusion caused!

@Alyssa: Can you please check whether the expanded limits are also given in the PAR? Based on CVwR 42.6% they should be close to

round(100 * scABEL(CV = 42.6 / 100), 1)
lower upper
 73.3 136.4


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