Agustin Lobo <firstname.lastname@example.org> wrote:
>I'm reading the doc for PLSgen2 by Luc Monimeau.
>Both the explanatory (X) and dependent matrices are
>20r x 3cols, but then the tk explanatory components are 20 x 4,
>why do we have one more component than initial variables?
This is an error in the listing. It has of course only 3 columns.
>Instead, in the "fiche" by Chessel and Monimeau, X is
>39 x 3 and Y is 39 x 15 (a better choice for an example, I think)
>and the VI.ivl1 (which I understand is the LS2 components of X,
>the file naming is very confusing, why not just X.PL2 ?)
>is 39 x 2 (becasue they select to keep only the first 2 components,
This is not in the PLS regression part of the document I think,
but in the part about instrumental variables (hence the "iv").
>Finally, Monimeau uses PLSgen2:Modelling, while Chessel and Monimeau use
>PCA on instrumental variables. Is this just a difference on soft versions?
No, principal component analysis on intrumental variables and
PLS regression are two different things. PCAIV is a PCA after
projection on a subspace. This is the same family of methods
as CCA (canonical correspondence analysis). PLS regression is
rather like co-inertia analysis methods.
-- Jean Thioulouse - Laboratoire de Biometrie - Universite Lyon 1 69622 Villeurbanne Cedex - France Fax: 04 78 89 27 19 Tel: 04 72 43 29 01 http://pbil.univ-lyon1.fr/ADE-4/JTHome.html
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