Science vs. regulations [Regulatives / Guidelines]

posted by Helmut Homepage – Vienna, Austria, 2020-05-07 23:54  – Posting: # 21405
Views: 2,107

Hi Achievwin,

» Then a priori in the protocol SAP include limitations on reporting AUCinf and %Extrp.
» 1. R2>0.800

Why this – arbitrary – number? Given, I have seen it in lots of SAPs.
\(\small{R^2}\) (strongly!) depends on the number of time points \(n\) (see this rather old thread). \(\small{R_{\textrm{adj}}^{2}}\) is better though still not independent from \(n\) (that’s a misconception sold by software vendors).
If clearance is variable and/or the analytical variability is high, a low correlation may be perfectly fine, whereas in the opposite case even 0.9 may indicate a poor fit. Unless you have data of a previous study with the same analytical method, IMHO, a pre-specified cut-off does not make sense.
Furthermore, never trust in results of a silicon-based life-form. Visual inspection of the fit is mandatory.

PS: 0.8 with three significant digits: 0.8005 is OK and 0.8004 not. Really?

Cheers,
Helmut Schütz
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