FA0(1) for partial replicate in Phoenix [RSABE / ABEL]

posted by Helmut Homepage – Vienna, Austria, 2013-08-07 15:13  – Posting: # 11235
Views: 6,380

Dear Detlew!

» Will try it the next time numerically.

Yes please. I tried John’s nasty data set (log-transformed data in full precision) where we ran into convergence problems and got different results for RSABE and ABE (we tried SAS and PHX; complete data set and after exclusion of incomplete data).
When I set up FA0(1) in PHX’ LME I got…
ERROR 11021: Variance matrix is not positive definite in QA.
… which is an indication that the initial variance estimates (by methods of moments) don’t “work”. I tried different starting values to no avail.

Now for the surprise: PHX’ BE-model (which supposedly sits ‘on top’ of LME) converged without a warning. I got

PE 101.0213% (90% CI: 80.7733–126.3450%) s²WR 0.42100 (CVWR 72.35%)

… matching Shuanghe’s and your’s in SAS with FDA’s FA0(2)-parameterization.
After exclusion of incomplete data (subjects 8, 14, 17, and 31)

PE  91.2423% (90% CI: 74.0705–112.3950%) s²WR 0.40652 (CVWR 70.82%)

… different to yours’.

Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. ☼
Science Quotes

Complete thread:

 Mix view
Bioequivalence and Bioavailability Forum |  Admin contact
19,405 posts in 4,122 threads, 1,323 registered users;
online 7 (0 registered, 7 guests [including 6 identified bots]).
Forum time (Europe/Vienna): 06:36 CEST

[Those] who have an excessive faith in their theories or in their
ideas are not only poorly disposed to make discoveries, but they
also make very poor observations.    Claude Bernard

BEBAC Ing. Helmut Schütz