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Re: st: how to get the components variable after -pca- or -fa-?


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: how to get the components variable after -pca- or -fa-?
Date   Tue, 3 Apr 2012 16:43:29 +0100

You do not spell out the precise commands you used for -pca- or -fa-,
although you went for factor analysis, it seems. But remember that by
default the variables must be standardised first to mean 0 and
variance 1. It doesn't seem that you did that.

Nick

2012/4/3 Grace Jessie <gracejessie@hotmail.com>:

>   Could anyone tell me how to get the  components variable after -pca- or -fa-?
> I know -predict f1- works well for the first component. However, I want to know how to calculate it? In my mind, it should equal each variable multiplied by its score. Disppointedly, it does not. Could anyone explain to me?
> for example,
>  predict p1
> (regression scoring assumed)
> Scoring coefficients (method = regression)
>    ------------------------
>        Variable |  Factor1
>    -------------+----------
>            dv21 |  0.28335
>            dv22 |  0.28218
>            dv23 |  0.28129
>            dv24 |  0.27461
>    ------------------------
> So P1=0.28335*dv21+0.28218*dv22+0.28129*dv23+0.27461*dv24? Why not?

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