[Rasch] Explained variance

Theo Dawson theo at devtestservice.com
Mon Oct 20 23:55:59 EST 2008


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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