Applying Multidimensional Item Response Theory to Renaissance Assessments to Enhance Diagnostic Reporting Capacity

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From the Executive Summary: "The goal of the Multidimensional Item Response Theory (MIRT) project for Renaissance is to increase the diagnostic reporting capacity for Renaissance assessments. The proposed methodology for meeting this goal was to evaluate the dimensionality of Renaissance Star items with respect to the learning progressions in math and reading. The learning progressions create testable hypotheses about the dimensional structure of the Star assessment items. This dimensionality was evaluated via MIRT models implied by the interrelated Skill Areas suggested by the learning progressions. Multidimensionality in the data was previously established by examining residual correlations from unidimensional Item Response Theory (IRT) calibrations of data. These residual correlations suggested that significant dimensionality was present in the data. After multidimensionality had been established, bi-factor MIRT models suggested by the Skill Area coding of items were fit to the data. These MIRT models showed significant improvement in model-data fit, thus validating the dimensionality hypotheses. Lastly, separate calibrations of items at different grade levels were linked to a common metric. This allows administration of items from across grade levels while still being able to produce scores on a constant scale. This report summarizes analyses for math and reading, gives insight into the meaning of Skill Areas, and demonstrates the added value of using MIRT for scaling."

AUTHOR: William P. Skorupski

The report is available online.

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