took just 52 hrs to do it :-) [🇷 for BE/BA]

posted by ElMaestro  – Denmark, 2020-07-13 16:18 (1233 d 15:13 ago) – Posting: # 21686
Views: 16,358

Hi Hötzi,


I think expressing the G matrix after this fit is a little backward;
The whole point is not to decompose V into ZGZt+R, because this design makes that decomposition pointless even when the design is otherwise relevant.
That SAS and WinNonlin and more do not have a way to make provisions for a solution outside those involving this decomposition, it merely a testament to their development capabilities than to the design itself. If you start defining the the stats model on basis of G and R rather than V then obviously you must create two variance components which are not uniquely estimable, but whose sum is. Therefore, just screw R and G, go directly for V, and present the components without in any way calling them members of G or R - they really aren't when the model is constructed my way.

The 2-trt, 3-seq, 3-per design is good, healthy and appropriate, until now it was just the statistical work on it that has been lagging. The post is an attempt at providing a solution.

Note also: The PE will be accessible via the est.b vector. You shuld be able to extract it (difference between first two effects, one good reason to do X without intercept) after the model has converged.

If you have a dataset that does not readily converge with SAS then I'd be eager to learn if it does in some flavour of my code. :-)
—
Pass or fail!
ElMaestro

Complete thread:

UA Flag
Activity
 Admin contact
22,811 posts in 4,783 threads, 1,641 registered users;
25 visitors (0 registered, 25 guests [including 8 identified bots]).
Forum time: 06:31 CET (Europe/Vienna)

Every man gets a narrower and narrower field of knowledge
in which he must be an expert in order to compete with other people.
The specialist knows more and more about less and less
and finally knows everything about nothing.    Konrad Lorenz

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5