Hello R-sig-ecology group,
I was wondering if anyone is aware of an example where PCA is used as a
predictive model? A community analysis example might be to predict the PC
values of a sample given its community composition. I had thrown this
question up on a statistics forum (
-ecology@r-project.org
Subject: [R-sig-eco] PCA as a predictive model
Hello R-sig-ecology group,
I was wondering if anyone is aware of an example where PCA is used as a
predictive model? A community analysis example might be to predict the PC
values of a sample given its community composition. I had
, Jari Oksanen
From: r-sig-ecology-boun...@r-project.org [
r-sig-ecology-boun...@r-project.org] on behalf of Marc Taylor [
marchtay...@gmail.com]
Sent: 23 May 2012 10:19
To: r-sig-ecology@r-project.org
Subject: [R-sig-eco] PCA as a predictive model
Subject: Re: [R-sig-eco] PCA as a predictive model
Hi Jari - one more question if you don't mind. Since the weights of the PCs are
related to the the amount of variance that they explain in the original data -
is it problematic to predict the PC scores with a second data set that has a
different
--
*From:* Marc Taylor [marchtay...@gmail.com]
*Sent:* 23 May 2012 11:55
*To:* Jari Oksanen
*Cc:* r-sig-ecology@r-project.org
*Subject:* Re: [R-sig-eco] PCA as a predictive model
Hi Jari - one more question if you don't mind. Since the weights of the
PCs are related to the the amount
On 05/23/2012 10:55 AM, Marc Taylor wrote:
Hi Jari - one more question if you don't mind. Since the weights of the PCs
are related to the the amount of variance that they explain in the original
data - is it problematic to predict the PC scores with a second data set
that has a different amount
Thank you Bob - you and Jari seem to be of consensus here :-)
I will have to double check that what I am doing really gives the same
result as predict.prcomp. My problem is that I have set up my PCA in a
slightly different way than you have - or for that matter, different from
many of the
