[Rasch] Explained variance

Michael Lamport Commons commons at tiac.net
Tue Oct 21 07:29:26 EST 2008


For hierarchical complexity and Rasch Score, the r2 are .8 or higher for the moral, social, social perspective taking, political domains, and .9 or above in math, physics, chemistry, and logic.  We share your opinion about the low r's.  Assessments are messier than instruments so r2 of .75 to .80 are very good.

MLC 

-----Original Message-----
>From: Theo Dawson <theo at devtestservice.com>
>Sent: Oct 20, 2008 8:55 AM
>To: Rasch Mailing List <Rasch at acer.edu.au>
>Subject: [Rasch] Explained variance
>
>Are there any established standards for the percentage of variance we  
>would like to see explained by the Rasch measure? Our cognitive  
>developmental assessments run 70%-80%, but for conventional tests we  
>have worked with the value is often lower than 30%.
>
>Also, for multiple choice tests, would it be typical for the first  
>factor from the residuals to have something to do with guessing?
>
>Theo
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My best,

Michael Lamport Commons, Ph.D.

Assistant Clinical Professor
Department of Psychiatry
Harvard Medical School

Program in Psychiatry and the Law
Beth Israel Deaconess Medical Center
commons at tiac.net

http://www.dareassociation.org/
617-497-5270 Telephone
617-491-5270 Fax



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