Re: st: RE: Negative eigen values in factor, pf command?

["Martin Weiss" <martin.weiss1@gmx.de>]

<>

"PS. if "Thanks emails" are inappropriate for the listserv,
please let me know off list and I'll refrain in the future...as I feel
I will be asking more questions soon)"


We can tell you this on the list, as it is plain to see from the FAQ 
http://www.stata.com/support/faqs/res/statalist.html#others
toward the end:

"Continuing or closing a thread you started is important, especially by 
answering secondary questions and by reporting what solved your problem. You 
can then thank those who tried to help. "

I hope that you will continue asking questions on the list :-)


HTH
Martin
_______________________
----- Original Message ----- 
From: "Jean-Gael Collomb" <JG@ufl.edu>
To: <statalist@hsphsun2.harvard.edu>
Sent: Wednesday, April 29, 2009 12:15 AM
Subject: Re: st: RE: Negative eigen values in factor, pf command?


> Thanks to all for the multiple and prompt answers. The latter posts  are 
> losing me, but they may be of interest to more statistically  curious 
> researchers (by the way, I did also try a factor, ml command,  and the 
> results also seemed different than the pca results). The basic 
> explanation of what was going on with the factor command was helpful  to 
> understand the negative eigen values and unblocked the discussion  with my 
> statistician colleagues.  I basically wanted to check the  dimensionality 
> of an index for a latent concept. I am going to put  more stock in the pca 
> results, and after looking at the factor  loadings, I feel in a better 
> position to interpret the results.
> Thanks (PS. if "Thanks emails" are inappropriate for the listserv,  please 
> let me know off list and I'll refrain in the future...as I feel  I will be 
> asking more questions soon)
> Cheers,
>
> Jean-Gael "JG" Collomb
> PhD candidate
> School of Natural Resources and Environment / School of Forest  Resources 
> and Conservation
> University of Florida
> jgcollomb@gmail.com
> jg@ufl.edu
> +1 (352) 870 6696
>
>
>
>
> On Apr 28, 2009, at 3:43 PM, Verkuilen, Jay wrote:
>
> > Michael I. Lichter wrote:
> >
> > > So what are you advocating instead? ML, which isn't very robust to
> > weirdness (technical term) in the data? Or something other than >FA/ PCA?
> >
> > No, I'm following the research of people like Rod McDonald (retired to
> > his beloved Sydney), Albert Maydeu-Olivares (Barcelona) and Bud  McCallum
> > (UNC-Chapel Hill), who support the use of the Unweighted Least Squares
> > criterion function, or multi-stage estimation methods that uses ULS
> > followed by a few iterations of ML or GLS. ULS is mathematically
> > equivalent to MINRES. Stata doesn't have ULS/MINRES (alas).
> >
> > One of the downsides to ULS is the fact that it doesn't generate
> > standard errors and GoF statistics, but Albert's been rectifying that
> > situation in a sequence of articles in various journals  (Psychometrika,
> > JASA, etc.): http://www.ub.edu/gdne/psicometriaen.html.
> >
> >
> >
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>
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