Open issues [🇷 for BE/BA]

posted by ElMaestro  – Denmark, 2020-08-06 21:11 (781 d 19:59 ago) – Posting: # 21827
Views: 11,618

(edited by ElMaestro on 2020-08-06 21:23)

Hi PharmCat,

I really like your idea. I don't have a good understanding of this as a whole but I know that when I work with a little these things they become easier for me to grasp, so I am giving it a try. :-)

Let us turn to Gurka 2006 equation 3 and 5 and remembering that the rank of our overall design matrix X is 6:
Gurka requires me to derive Xi, the design matrix for fixed effects of subject i.
They mention that "Xi is a (ni × p) known, constant design matrix for the i' th subject
with rank p"

At just three observations per subject we cannot have a rank of p=6 for Xi. The maximum rank is naturally 3. I don't see a way to handle Xi on a subject by subject basis, but perhaps you have some insight. Possibly I could do it by lumping subjects together so that the "smaller" X of sorts still has more rows thank columns and thus a rank of p=6.


Do you see my issue with Xi? Could you indicate your view on Xi here? Is lumping subjects together a way to go to ensure the right rank of the reduced design matrices? Many thanks in advance.

Pass or fail!
ElMaestro

Complete thread:

UA Flag
Activity
 Admin contact
22,391 posts in 4,685 threads, 1,594 registered users;
online 25 (0 registered, 25 guests [including 24 identified bots]).
Forum time: Tuesday 17:10 CEST (Europe/Vienna)

Statistics. A sort of elementary form of mathematics which consists of
adding things together and occasionally squaring them.    Stephen Senn

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