s2wR != mse, FDA != EMA [General Sta­tis­tics]

posted by Helmut Homepage – Vienna, Austria, 2017-03-06 13:40 (1735 d 11:09 ago) – Posting: # 17138
Views: 15,487

Hi VStus,

» » But s2wR = MSE is not necessarily true in all cases, although it is in many cases a reasonable assumption.
» And s2wR != s2wT in most cases. Maybe that's the reason why 2x3x3 design is still so popular. It's not possible to assess s2wT...

No agency asks for s²wT in the context of RSABE or ABEL (the FDA’s RSABE for NTIDs is another story but requires a 4-period full replicate anyhow). Hence, why should one report it? :-D
I never understood why one would opt for the partial replicate. Does this equation hold?

Partial replicate = lack of statistical knowledge + “we want only three periods” + given in the FDA’s guidance / the EMA’ Q&A-document (as an example)?

IMHO, at least in pilot studies full replicates are preferable (see there). I once struggled with a Romanian CRO. The sponsor decided to perform a 4-period full replicate in order to possibly end up with a smaller sample size of the pivotal study if CVwT < CVwR. The CRO refused to calculate CVwT (“… because not in accordance with the SAS-code given in the Q&A.”)… Oh boy! Only after the sponsor threatened to go with another CRO, they gave in.

Dif-tor heh smusma 🖖
Helmut Schütz

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