Too coarse grid? [Two-Stage / GS Designs]

posted by Helmut Homepage – Vienna, Austria, 2024-03-10 21:49 (40 d 14:29 ago) – Posting: # 23898
Views: 701

Hi ElMaestro,

❝ Potvin's idea, one that was copied in subsequent papers form various authors is to evaluate a range of CV's and GMR's that cover most naturally occurring combinations. You never know the true GMR or a true CV - you just get some estimates. The grid of combinations (CV, GMR) is then chosen so as to be dense enough that we're comfortable to conclude that once we've found good alphas there will not be overall alpha inflation even for a true (CV, GMR) not falling exactly on a grid point. Some like it, some don't.

The Czech SÚKL didn’t like it last year. I saw a deficiency letter lamenting that “Potvin’s grid was too coarse and it cannot be guaranteed that the type I error is controlled.”
Showed them this one (step size of n1 = 2, step size of CV = 1%). Case closed.

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