Bookmark and Share

Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down on April 23, and its replacement, statalist.org is already up and running.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

st: AW: vce matrix manipulation in pca


From   Sheela Athreya <athreya@tamu.edu>
To   statalist@hsphsun2.harvard.edu
Subject   st: AW: vce matrix manipulation in pca
Date   Sat, 7 Aug 2010 12:09:20 -0500

Martin,

Thank you for the advice. It's very helpful.  I used "_00001" because it was one of two matrices in my pulldown menu when I used the "define matrix" command window, after running the PCA.  I figured it was temporary and hence I couldn't really manipulate it.

Is there a way to compute PC scores based on a new data set but using a pre-defined vce matrix? (The C matrix below that you helped me define)

Many thanks,
Sheela



> Date: Fri, 6 Aug 2010 09:44:42 +0200
> From: "Martin Weiss" <martin.weiss1@gmx.de>
> Subject: st: AW: vce matrix manipulation before and after pca
> 
> <> 
> 
> Technically, you can do it like this, but I am not sure whether the result
> is meaningful in any way:
> 
> *************
> sysuse auto, clear
> pca trunk weight length headroom if foreign, vce(normal)
> mat A=e(V)
> pca trunk weight length headroom if !foreign, vce(normal)
> mat B=e(V)
> mat C=(A+B)/2
> mat l C
> *************
> 
> 
> Where did you get the idea to use "__000001"? These are temporary objects
> which you cannot access the way you tried to...
> 
> 
> HTH
> Martin
> 
*******************************
Sheela Athreya, Ph.D.
Department of Anthropology
Texas A&M University
College Station, TX  77843

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   Site index