"normal" GMR setting [Power / Sample Size]

posted by d_labes  – Berlin, Germany, 2017-12-28 18:57  – Posting: # 18117
Views: 18,999

Dear Helmut,

» ...Taking into account that the analytical method used for measuring the content of test- and reference-batches has limited accuracy/precision (2.5% is excellent!) and the method is not validated for the reference (you can ask the innovator for a CoA but never ever will get it) 0.95 might be “normal” ...

"Normal" is a question one could debate for hours, probably ending in a flame war :-D.
For me 0.95 or 1/0.95 is as "normal" like setting alpha = 0.05.
It's a convention to be used if nothing specific about the GMR is known. Nothing more.
And it seemed mostly to work over the years I have observed the use of this setting.
Of course it is not a natural constant.

Clinically relevant difference (aka GMR in bioequivalence studies): That which is used to justify the sample size but will be claimed to have been used to find it.
Stephen Senn

» ... but IMHO, optimistic even if you measure a content of 100% for both T and R. Given that power is most sensitive to the GMR I question the usefulness of 0.95.

Any other suggestion instead of 0.95 :confused:



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