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. 2016 Jun;76(3):412-435.
doi: 10.1177/0013164415594202. Epub 2015 Jul 7.

Controlling Guessing Bias in the Dichotomous Rasch Model Applied to a Large-Scale, Vertically Scaled Testing Program

David Andrich  1 , Ida Marais  1 , Stephen Mark Humphry  1
Affiliations

Controlling Guessing Bias in the Dichotomous Rasch Model Applied to a Large-Scale, Vertically Scaled Testing Program

David Andrich et al. Educ Psychol Meas. 2016 Jun.

Abstract

Recent research has shown how the statistical bias in Rasch model difficulty estimates induced by guessing in multiple-choice items can be eliminated. Using vertical scaling of a high-profile national reading test, it is shown that the dominant effect of removing such bias is a nonlinear change in the unit of scale across the continuum. The consequence is that the proficiencies of the more proficient students are increased relative to those of the less proficient. Not controlling the guessing bias underestimates the progress of students across 7 years of schooling with important educational implications.

Keywords: Rasch model; guessing; large-scale assessments; multiple-choice items; vertical scaling.

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Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
ICC for the 3PL, a modified 3PL, and the dichotomous Rasch model.
Figure 2.
Figure 2.
Origin-equated plotted against the tailored item difficulties.
Figure 3.
Figure 3.
Origin-equated plotted against the all-anchored person estimates.
Figure 4.
Figure 4.
Year group means for three analyses.
Figure A1.
Figure A1.
ICC and observed means in five class intervals disaggregated by Years 3 and 5 from the initial analysis.
Figure A2.
Figure A2.
ICC of Item 3.26 and observed means in five class intervals in the tailored analysis disaggregated by Years 3 and 5.
Figure A3.
Figure A3.
ICC of Item 3.26 and observed means in five class intervals disaggregated by Years 3 and 5 in the all-anchored analysis.
Figure B1.
Figure B1.
Item estimates from the simulation study.
Figure B2.
Figure B2.
Person estimates from the simulation study (Tailored estimates cover the simulated values).
See this image and copyright information in PMC

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References

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