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 ordinati
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 o
bles, and applies those
> to your 'newdata' before rotating to PCs.
>
> Cheers, Jari Oksanen
> --
> *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
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 of variance that they explain in the original data -
is it problematic to p
(CCA,
>> RDA) from community composition, also with 'newdata' communities.
>>
>> Cheers, Jari Oksanen
>>
>>
>> From: r-sig-ecology-boun...@r-project.org [
>> r-sig-ecology-boun...@r-project.org] on behalf
n (CCA, RDA) from
> community composition, also with 'newdata' communities.
>
> Cheers, Jari Oksanen
>
>
> From: r-sig-ecology-boun...@r-project.org [
> r-sig-ecology-boun...@r-project.org] on behalf of Marc Taylor [
> march
ay...@gmail.com]
Sent: 23 May 2012 10:19
To: r-sig-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
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 (
http://stats.stacke