[Rasch] Incredible comments on Rasch

Michael Lamport Commons commons at tiac.net
Thu Oct 5 23:00:24 EST 2006


We regularly publish papers using Rasch on attitudes towards and of Expert Witness.  I can send you the references if you like.  I think that reliability is built into one of the Rasch tables.

My Best,

Michael Lamport Commons, Ph.D.
Assistant Clinical Professor
Program in Psychiatry and the Law
Department of Psychiatry
Harvard Medical School
Beth Israel Deaconess Medical Center
234 Huron Avenue
Cambridge, MA 02138-1328

Telephone (617) 497-5270
Facsimile (617) 491-5270
Commons at tiac.net
http://dareassociation.org/



  ----- Original Message ----- 
  From: Jakob Bjorner 
  To: Reeve, Bryce (NIH/NCI) [E] ; Eric Wong ; rasch at acer.edu.au 
  Sent: Thursday, October 05, 2006 8:44 AM
  Subject: RE: [Rasch] Incredible comments on Rasch


  Dear Eric,

  In my opinion, the two sentences:

  'The proposed validation analysis (using Rasch modelling) is not appropriate for a questionnaire focusing on attitude and behaviour and should be revised.'

  And 

  '. Rasch analysis for the valdiation/reduction of items is not appropriate because the items on attitude or usage do not have a linear order, unlike educational assessment .'

  represent a misunderstanding of the Rasch model. Certainly, Rasch models can be used to analyze questionnaires on attitude and behavior. However, Rasch analysis can be applied in many different ways, some of which may be more or less helpful depending on the situation. E.g. some researchers would estimate the location parameter (mean of the item thresholds) for each item and exclude items that had location parameters too similar to other items. That may be a good strategy if you want a test with a clear hierarchical order of items, but may not be a good idea in the present situation. It seems to me that the reviewers are taking issue with such an approach. However, that is only one way to use the Rasch model. Mathematically, the model can still be valid, even if all items have the same location (this is the sort of test you would want in a fail-pass situation).

  I agree with Bryce and the reviewers that know group comparison, concurrent validity, and construct/criterion validity can be valuable additions to a Rasch analysis. These approaches are not mutually exclusive.

  Hope this helps.

  Jakob

   

  Jakob Bue Bjorner, MD, PhD
  Chief Science Officer
  QualityMetric Incorporated
  640 George Washington Highway, Suite 201 
  Lincoln, RI  02865
  Phone: (401) 334-8800, ext. 271
  Fax: (401) 334-8801
  jbjorner at qualitymetric.com 
  www.qualitymetric.com
  www.sf-36.org


------------------------------------------------------------------------------

  From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On Behalf Of Reeve, Bryce (NIH/NCI) [E]
  Sent: Friday, September 29, 2006 1:21 PM
  To: Eric Wong; rasch at acer.edu.au
  Subject: RE: [Rasch] Incredible comments on Rasch

   

  Dear Eric and colleagues,

   

  I do not know what you proposed, but from the comments below it seems like they are saying that a full validation of the IMAQ questionnaire should include a number of different validation methodologies/strategies, not just Rasch analysis.  I agree, Rasch analysis gives you some information but not the full picture.  In validating the IMAQ, you should consider the questionnaire's construct validity (e.g., convergent and divergent validity), content validity, and criterion validity.  These different types of validation require different methods.  By itself, one method does not address all aspects of questionnaire validation.

   

  Sincerely,

  -Bryce

   


------------------------------------------------------------------------------

  From: Eric Wong [mailto:mcwong at cuhk.edu.hk] 
  Sent: Friday, September 29, 2006 5:16 AM
  To: rasch at acer.edu.au
  Subject: [Rasch] Incredible comments on Rasch
  Importance: High

   

    Dear all,

    Unbelievable comments from reviewers of a research grant review board:

    "The questionnaire should be shortened. The proposed validation analysis (using Rasch modelling) is not appropriate for a questionnaire focusing on attitude and behaviour and should be revised."

    "The methods proposed for the adpatation of the content of the IMAQ (the questionnaire) are well written, but Rasch analysis for the valdiation/reduction of items is not appropriate because the items on attitude or usage do not have a linear order, unlike educational assessment. More standard methods, such as know group comparison or concurrent validity, for validating the construct/criterion validity of the IMAQ should be used."

    Any comments?

     

    Eric 

   



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