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Education Commons

Open Access. Powered by Scholars. Published by Universities.®

2013

Educational Psychology

University of Iowa

Educational Measurement

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Full-Text Articles in Education

Effect Of Violating Unidimensional Item Response Theory Vertical Scaling Assumptions On Developmental Score Scales, Anna Marie Topczewski Jul 2013

Effect Of Violating Unidimensional Item Response Theory Vertical Scaling Assumptions On Developmental Score Scales, Anna Marie Topczewski

Theses and Dissertations

Developmental score scales represent the performance of students along a continuum, where as students learn more they move higher along that continuum. Unidimensional item response theory (UIRT) vertical scaling has become a commonly used method to create developmental score scales. Research has shown that UIRT vertical scaling methods can be inconsistent in estimating grade-to-grade growth, within-grade variability, and separation of grade distributions (effect size) of developmental score scale. In particular the finding of scale shrinkage (decreasing within-grade score variability as grade-level increases) has led to concerns about and criticism of IRT vertical scales. The causes of scale shrinkage have yet ...