, Volume 84, Issue 1, pp 310–322 | Cite as

Optimal Scores: An Alternative to Parametric Item Response Theory and Sum Scores

  • Marie WibergEmail author
  • James O. Ramsay
  • Juan Li


The aim of this paper is to discuss nonparametric item response theory scores in terms of optimal scores as an alternative to parametric item response theory scores and sum scores. Optimal scores take advantage of the interaction between performance and item impact that is evident in most testing data. The theoretical arguments in favor of optimal scoring are supplemented with the results from simulation experiments, and the analysis of test data suggests that sum-scored tests would need to be longer than an optimally scored test in order to attain the same level of accuracy. Because optimal scoring is built on a nonparametric procedure, it also offers a flexible alternative for estimating item characteristic curves that can fit items that do not show good fit to item response theory models.



This research was funded by the Swedish Research Council Grant 2014-578.

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Copyright information

© The Psychometric Society 2018

Authors and Affiliations

  1. 1.USBE, Department of StatisticsUmeå UniversityUmeåSweden
  2. 2.Department of PsychologyMcGill UniversityMontrealCanada
  3. 3.Department of Mathematics and StatisticsMcGill UniversityMontrealCanada

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