Bioequivalence and Bioavailability Forum • Not understood

Not understood [🇷 for BE/BA]

posted by ElMaestro – Denmark, 2020-08-05 10:13 (1218 d 22:39 ago) – Posting: # 21824
Views: 13,347

Thanks PharmCat,

funny, I read the ref. you mention (Lindstrom & Bates) yesterday and I did not understand much of it. Will try again.

❝ Problem1: when you have big matrix invercing is slow as hell, but if you inverce by blocks (you can do it because it block-diagonal) it can be done faster.

Sounds neat, will check if I can somehow do such a thing.

❝ Problem2: In BE case you have many equal Z_i matrices, so in logREML calculation (if you calc by subject) you inverce one matrix many times (because V = ZGZ'+R, Z can be different, G and R not changing subject by subject). If you cache result - you can seriously increase performance.

My approach is very simple: I make a case for saying that when T is not replicated while R is replicated, then it is not possible to make a meaningful model when V=ZGZt+R (as long as we count on R having the withins and G having the betweens). If we insest on ZGZt+R then we get irrelevant variance components associated with T whichever way we parameterise the covariance matrix. Therefore, I am working in V directly, meaning I am writing the blocks into it directly.
This may still be compatible with your proposal, though.

—
Pass or fail!
ElMaestro

Complete thread:

Semireplicated + REML in R ElMaestro 2020-07-10 13:19 [🇷 for BE/BA]
- Semireplicated + REML in R Helmut 2020-07-10 19:03
  - Semireplicated + REML in R ElMaestro 2020-07-10 19:24
    - Avoid partial replicate designs, pleeeze! Helmut 2020-07-11 11:57
      - Avoid partial replicate designs, pleeeze! ElMaestro 2020-07-11 14:43
        
        Braveheart! Helmut 2020-07-11 15:38
        
        Who can help? ElMaestro 2020-07-12 12:28
        
        Who can help? ElMaestro 2020-07-12 13:26
        Update II ElMaestro 2020-07-12 21:36
        
        Update III ElMaestro 2020-07-12 21:46
        
        Final update today ElMaestro 2020-07-12 22:27
        
        Medium rare. Helmut 2020-07-13 13:52
        
        took just 52 hrs to do it :-) ElMaestro 2020-07-13 14:18
        
        Will take much more hours still… Helmut 2020-07-13 15:34
        
        Negative determinant ElMaestro 2020-07-14 03:22
        
        Are we loosers? Helmut 2020-07-14 13:58
        
        "we"? Loosers? ElMaestro 2020-07-14 15:07
        
        Misunderstanding? Helmut 2020-07-14 15:32
        
        Braveheart! ElMaestro 2020-07-13 10:13
        
        Braveheart! Helmut 2020-07-13 14:16
        Braveheart! PharmCat 2020-07-15 14:19
        
        Braveheart! ElMaestro 2020-08-02 17:39
- We were all blind (except Detlew) Helmut 2020-07-15 14:27
  - It is the opposite way around for me ElMaestro 2020-07-15 16:25
    - Desultory thoughts Helmut 2020-07-15 17:33
      - FDA RSABE is ISC d_labes 2020-07-15 18:13
        
        FDA RSABE is ISC Helmut 2020-07-16 11:11
      - Desultory thoughts ElMaestro 2020-07-15 23:06
        
        Desultory thoughts Helmut 2020-07-16 10:59
  - Phoenix - which template? mittyri 2020-07-19 00:42
    - FDA RSABE Project template_ v1.4.phxproj Helmut 2020-07-19 01:45
- "By popular demand": likelihood ElMaestro 2020-07-24 10:07
  - And by the way.... ElMaestro 2020-07-24 12:52
    - And by the way.... PharmCat 2020-08-03 14:24
      - Not understood ElMaestro 2020-08-03 22:55
        
        Not understood PharmCat 2020-08-05 01:41
        
        Not understoodElMaestro 2020-08-05 08:13
        
        Not understood PharmCat 2020-08-05 16:37
        
        Open issues ElMaestro 2020-08-06 21:11
        
        Open issues PharmCat 2020-08-07 00:02
        
        Open issues ElMaestro 2020-08-07 07:49
        
        Open issues PharmCat 2020-08-07 11:29
        
        Still can't make it work ElMaestro 2020-08-07 13:08
        
        Still can't make it work PharmCat 2020-08-07 15:42
        
        Still can't make it work ElMaestro 2020-08-07 16:44
        
        Still can't make it work PharmCat 2020-08-07 18:14
        
        Still can't make it work ElMaestro 2020-08-07 18:23
        
        And now it works ElMaestro 2020-08-07 21:31
        Still can't make it work PharmCat 2020-08-08 01:08
        
        Speed improvement ElMaestro 2020-08-08 12:25
        
        Speed improvement PharmCat 2020-08-08 17:27
        Speed improvement ElMaestro 2020-08-08 18:10
        
        Speed improvement PharmCat 2020-08-09 18:22
        Some tests... PharmCat 2020-08-10 11:48