Still can't make it work [🇷 for BE/BA]

posted by ElMaestro  – Denmark, 2020-08-07 15:08 (1389 d 04:57 ago) – Posting: # 21831
Views: 13,911

Hi PharmCat,

thanks for trying to assist on this. :-) It is kind of you.

❝ I think Xi is not shuld be full-rank design matrix. It is just part of X for subject i. Moreover all Xi should be the same width (num of columns) for Σ(Xi'V-1Xi). Also with (yi - Xi*β) you get residuals ri (col num of Xi should be equal length β).

❝ There is not very accurate description in Gurka's paper, but it provide good concept.

❝ If you check, it should work.


I can't make it work.
In Gurka's equation 3, where we can write the shorthand beta= M1-1*M2: When using the little 3-by-6 matrices for Xi, M1 becomes non-invertible.
I tried to lump 6 subjects together at a time, and now I am getting an estimate of beta but it appears wrong, in the sense it is not corresponding to what I get for the full model.

I wonder if Gurka's equation only works under assumptions not mentioned in the paper or if I am just a very lousy programmer. My money is clearly on the latter :-D

Pass or fail!
ElMaestro

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