[Rasch] Rasch vc CFA

Svend Kreiner svkr at sund.ku.dk
Sat Sep 29 17:37:10 EST 2012


If they are using factor analysis to "find" the factors they are doing exploratory factor analysis. Confirmatory factor analysis is supposed to start with a theory just like the Rasch model and then estimates parameters and assess the data-model fit. One of the underlying assumptios is that the latent variable is assumed to be normal, for which reason CFA is similar to marginal estimation in Rasch models. There is nothing special about CFA. It's just another model. If we have reasons to prefer the Rasch models to other models there is no reason to look at CFA at all.

Svend
________________________________________
From: rasch-bounces at acer.edu.au [rasch-bounces at acer.edu.au] on behalf of Bond, Trevor [trevor.bond at jcu.edu.au]
Sent: Saturday, September 29, 2012 1:51 AM
To: rasch at acer.edu.au
Subject: Re: [Rasch] Rasch vc CFA

Yes, I know of those who use CFA to find the factors and then subject each factor to RM.
Why? I don't know.
I'd rather start with a theory which describes how the variable should look, and use RM to examine that…

From: Michael Lamport Commons <commons at tiac.net<mailto:commons at tiac.net>>
Reply-To: "rasch at acer.edu.au<mailto:rasch at acer.edu.au>" <rasch at acer.edu.au<mailto:rasch at acer.edu.au>>
Date: Saturday, 29 September 2012 3:07 AM
To: "rasch at acer.edu.au<mailto:rasch at acer.edu.au>" <rasch at acer.edu.au<mailto:rasch at acer.edu.au>>
Subject: Re: [Rasch] Rasch vc CFA

The only problem I have is should I use factor analysis to find the a-priori dimensions.  I always follow up with a Rasch Analysis.  Two things were left out   The number of types of questions makes a big difference and the culture of the respondents.  With Rasch, this does not seem to be the case to any degree.

My Best,

Michael Lamport Commons, Ph.D.
Assistant Clinical Professor

Department of Psychiatry
Beth Israel Deaconess Medical Center
Harvard Medical School
234 Huron Avenue
Cambridge, MA 02138-1328

Telephone   (617) 497-5270
Facsimile   (617) 491-5270
Cellular    (617) 320–0896
Commons at tiac.net<mailto:Commons at tiac.net>http://dareassociation.org/

On 9/28/2012 2:16 AM, Bond, Trevor wrote:

Just like fit to the Rasch model...


but real life is not perfect!


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