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The Effects Of Scaling On Trends Of Development: Classical Test Theory And Item Response Theory, Weldon Z. Smith

College of Education and Human Sciences: Dissertations, Theses, and Student Research

The scale metrics used in educational testing are often arbitrary, and this can impact interpretation of scores on measurements. Both classical test theory sum scores and item response theory estimates measure the same underlying dimension, but differences in the two scales may lead one to be more preferential than the other in interpreting data. Mismatch between individual ability and test difficulty can further result in difficulties in correctly interpreting trends of development in longitudinal data. A previous limited simulation by Embretson (2007) demonstrated that classical test theory sum scores result in misinterpretation of linear trends of development, and that item …