[Rasch] Rasch analysis then EFA

Juanito Talili talilij at yahoo.com
Fri Nov 18 15:45:40 EST 2011


My apology for the low level questions:
 
1. What is the logic why the residuals of the Rasch analysis are subjected for EFA?  Why not the person or item measures? 
2. The factors in the previous analysis were correlated. Should I do Rasch on the combined items?
 
Thank you.
J

From: "Swank, Paul R" <Paul.R.Swank at uth.tmc.edu>
To: Juanito Talili <talilij at yahoo.com>; Rasch Forum <rasch at acer.edu.au> 
Sent: Thursday, November 17, 2011 10:41 PM
Subject: RE: [Rasch] Rasch analysis then EFA


I would do the Rasch on all classes in order to increase heterogeneity of responses. And I would suggest EFA on the residuals of the Rasch analysis. It all depends on whether the factors are correlated so that it is possible there is an underlying latent variable with perhaps some specific factors. If the factors in the previous analysis were uncorrelated, then I would think twice before using Rasch on the combined items.
 
Dr. Paul R. Swank, 
Children's Learning Institute
Professor, Department of Pediatrics, Medical School
Adjunct Professor, School of Public Health
University of Texas Health Science Center-Houston
 
From:rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On Behalf Of Juanito Talili
Sent: Wednesday, November 16, 2011 11:57 PM
To: Rasch Forum
Subject: [Rasch] Rasch analysis then EFA
 
 
Opps!! I forgot to indicate the subject.
Dear All,
 
A self-administered "Computer Laboratory Usability Questionnaire" consists of 43 five-point ordinal scale items (1=strongly disagree to 4 strongly agree).  The instrument, moreover, consists of six factors with the following number of items: 3, 3, 4, 7, 12, and 15.  The questionnaire was developed using CTT.
 
My Concerns:
1) Now, I want to re-validate the instrument using Rasch Model.  My sample now is already more than 3000.  The samples are students who rated six different computer laboratories (LAB1, LAB2....LAB6).  Shall I use only sample from one LAB?
 
2. Can I do the Rasch analysis for the 43 items as if unidimensional?  Then, do an EFA using the resulting measures?  The EFA will be used to check if the items are really loaded to the expected factor.
 
Your comments are highly solicited.
 
Thank you.
J
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