[Rasch] Validation & Rasch

Mike Linacre (RMT) rmt at rasch.org
Fri Nov 23 06:46:33 EST 2007


James:

Thank you for classifying our technical activities regarding test validity.
For the traditionalists, please add:
6. Reliability.

Please also add these conceptual (and more important) activities:
A. Construct validity: Investigating what the test is actually measuring, 
usually through the item hierarchy from less to more.
B. Predictive validity: Investigating whether what the test is measuring 
accords with the person hierarchy from less to more.
C. Misfit diagnosis: Investigating what treasure (to be mined) or trash (to 
be thrown out)  is also present in our test responses.
D. Communicating findings: no matter how valid a test is psychometrically, 
if its consumers misunderstand or misuse its findings, its practical 
validity is compromised.

OK?

Mike L.

At 11/22/2007, you wrote:
>Looking over papers which have used Rasch methodology to validate tests, I 
>found out a number of procedures for validating
>1. Studying fit stats.
>2. Checking threshold ordering
>3. Assessing unidimensionality using PCA of residuals
>4. Investigating DIF
>5. Checking person measure invariance over subsets of the test

Mike Linacre
Editor, Rasch Measurement Transactions
rmt at rasch.org www.rasch.org/rmt/ Latest RMT:  21:2 Autumn 2007
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