Bioequivalence and Bioavailability Forum • SAS vs. PHX/WNL

SAS vs. PHX/WNL [Bioanalytics]

posted by Helmut – Vienna, Austria, 2014-09-28 19:21 (3894 d 01:11 ago) – Posting: # 13606
Views: 12,769

Hi to all,

❝ This could be the case if there is one or more subjects having some period data missing; didn't I read somewhere that WNL will do a max likelihood optimisation by default (=essentially a mixed model) whereas SAS will try Proc GLM (normal linear model).

❝ The mixed model versus normal linear model would explain the subtle difference which then isn't a matter of decimals carried.

Correct for WinNonlin. SAS doesn’t try “Proc GLM” – it will use it if stated in the code (actually what John did). If we have incomplete data (period missing) we should get identical results if all data are kept:

SAS Proc mixed = WinNonlin’s default random effects model evaluated by REML.
SAS Proc GLM = WinNonlin all fixed effects model: random effect subject(sequence) deleted and added to the fixed effects.

If incompleted cases are excluded (as sugested by the EMA for nonreplicated studies), any software / model should give the same results anyway. See also there.

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    - Reporting of plasma concentration data etc Ohlbe 2014-09-28 13:53
  - Reporting of plasma concentration data etc ElMaestro 2014-09-28 15:07
    - SAS vs. PHX/WNLHelmut 2014-09-28 17:21
- Numbers should reflect the precision of the instrumentation Helmut 2014-09-28 19:34