RE: 2B-PLS vs PLSR

morphmet_moderator Sun, 28 Apr 2013 18:55:51 -0700

----- Forwarded message from Rodrigo Lima <[email protected]> -----

Date: Sun, 28 Apr 2013 18:02:16 -0400
From: Rodrigo Lima <[email protected]>
Reply-To: Rodrigo Lima <[email protected]>
Subject: RE: 2B-PLS vs PLSR
To: "[email protected]" <[email protected]>

Thanks to all who posted their advice here, I really appreciate it.

Milos, I haven't tried the plsdepot package but it seems to me that the plsreg2 function is the analysis that would be used for geometric morphometrics.

Best wishes,
Rodrigo

From: [email protected] [[email protected]]
Sent: April 28, 2013 2:25 AM
To: [email protected]
Subject: RE: 2B-PLS vs PLSR

----- Forwarded message from Milos Blagojevic <[email protected]> -----

Date: Sat, 27 Apr 2013 10:30:59 -0400
From: Milos Blagojevic <[email protected]>
Reply-To: Milos Blagojevic <[email protected]>
Subject: RE: 2B-PLS vs PLSR
To: "[email protected]" <[email protected]>

Dear Dean and Rodrigo,

Can I just ask about the plsdepot R-package from Gaston Sanchez (http://www.gastonsanchez.com/plsdepot)? It seems to have several algorithms for the PLS implemented, but regardless all of them differ in results for PLS (I tried my dataset) in comparison to pls package and calculation by hand.

Have you tried this package?

Best regards,

Milos

From: [email protected]
To: [email protected]
Subject: Re: 2B-PLS vs PLSR
Date: Sat, 27 Apr 2013 00:05:35 -0700

----- Forwarded message from Dean Adams <[email protected]> -----

Date: Fri, 26 Apr 2013 10:20:35 -0400
From: Dean Adams <[email protected]>
Reply-To: Dean Adams <[email protected]>
Subject: Re: 2B-PLS vs PLSR
To: [email protected]

Rodrigo,

The two methods are identical; plsr() is just an implementation of two-block partial least squares. To obtain the PLS correlation between primary PLS vectors in plsr(), do:

pls.res<- plsr(Y ~ X)
cor(pls.res$scores[,1],pls.res$Yscores[,1])

The same result could also be found 'by hand' following the steps in Rohlf and Corti 2000: obtain the cross-covariance matrix S.XY, decompose it via SVD, project the data onto the vectors, and find their correlation.

Dean

--
Dr. Dean C. Adams
Professor
Department of Ecology, Evolution, and Organismal Biology
Department of Statistics
Iowa State University
Ames, Iowa
50011
www.public.iastate.edu/~dcadams/
phone: 515-294-3834

On 4/25/2013 4:45 PM, [email protected] wrote:

----- Forwarded message from Rodrigo Lima <[email protected]> -----

Date: Wed, 24 Apr 2013 09:57:46 -0400
From: Rodrigo Lima <[email protected]>
Reply-To: Rodrigo Lima <[email protected]>
Subject: 2B-PLS vs PLSR
To: "[email protected]" <[email protected]>

Dear morphometricians,

I have a question about the PLS analysis and I would be very thankful for any insight provided.

What is the difference between two-block PLS (as in Rohf and Corti 2000) and PLS regression (PLSR) implemented in the pls package in R (Mevik and Wehrens 2007)? I'm trying to relate skull shape to climatic variables, which one would be more appropriate in this case?

Thank you,
Rodrigo

----- End forwarded message -----

----- End forwarded message -----

RE: 2B-PLS vs PLSR

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