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Re: st: PCA with Missing Values (or other factor analysis)


From   Nick Eubank <nickeubank@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: PCA with Missing Values (or other factor analysis)
Date   Tue, 5 Jul 2011 09:03:19 -0700

No worries! Thanks for giving it a shot!

On Tuesday, July 5, 2011, David Svendsgaard
<Svendsgaard.David@epamail.epa.gov> wrote:
> I gave you the wrong answer. I thought you were trying to predict votes
> with some independent variables and you were using PCA
> scores of these independent variables as the predictors.
>
> It sounds like you have classified the subject of the vote, somehow. I
> don't have an answer for this.
>
> Sorry for the confusion.
>
>
>
>
>
> David J Svendsgaard, PhD
> Biostatistician
> EPA/ORD/NCEA/RTP, Mail Drop B-243-01
> Research Triangle Park, NC 27711
> Phone (919) 541-4186
> Fax (919) 541-1818
>
>
>
> From:   Nick Eubank <nickeubank@gmail.com>
> To:     statalist@hsphsun2.harvard.edu
> Date:   07/03/2011 12:17 AM
> Subject:        st: PCA with Missing Values (or other factor analysis)
> Sent by:        owner-statalist@hsphsun2.harvard.edu
>
>
>
> Hello All,
>
> I'm trying to do a PCA on legislator votes (1 or 0), where different
> legislators have overlapping but distinct terms. In other words,
> legislator A is in office periods 1 and 2, legislator B is in office 2
> and 3, so A has no votes in period 3 and B has no votes in period A. I
> want to map their "ideal points" (i.e. pca predicted value from votes)
> into the same space. But PCA obviously dislikes missing values.
>
> Suggestion? I'm really open to any factor analysis algorithm.
>
> Thanks!
>
> Nick
>
>
>
> --
> PhD Student, Political Economics
> Stanford University GSB
> nickeubank@gmail.com
> Cell: +1 (303) 918.6528
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-- 
PhD Student, Political Economics
 Stanford University GSB
nickeubank@gmail.com
Cell: +1 (303) 918.6528

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