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’.
Amazing.

Cheers,
Helmut Schütz
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