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Agustin Lobo <alobo@ija.csic.es> wrote:

*>I'm reading the doc for PLSgen2 by Luc Monimeau.
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*>Both the explanatory (X) and dependent matrices are
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*>20r x 3cols, but then the tk explanatory components are 20 x 4,
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*>why do we have one more component than initial variables?
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This is an error in the listing. It has of course only 3 columns.

*>Instead, in the "fiche" by Chessel and Monimeau, X is
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*>39 x 3 and Y is 39 x 15 (a better choice for an example, I think)
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*>and the VI.ivl1 (which I understand is the LS2 components of X,
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*>the file naming is very confusing, why not just X.PL2 ?)
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*>is 39 x 2 (becasue they select to keep only the first 2 components,
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*>I guess).
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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
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*>PCA on instrumental variables. Is this just a difference on soft versions?
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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

-- 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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