Optimal number of strata for the stratified methods in computerized adaptive testing
Entity
UAM. Departamento de Psicología Social y MetodologíaPublisher
Cambridge University PressDate
2014-07-08Citation
10.1017/sjp.2014.50
Spanish Journal of Psychology 17 (2014): e48
ISSN
1138-7416 (print); 1988-2904 (online)DOI
10.1017/sjp.2014.50Funded by
This research was supported by a grant from the Spanish Ministerio de Ciencia e Innovación (project number PSI2009–10341), and by a grant from the Fundación Universitaria Antonio Gargallo and the Obra Social de Ibercaja.Project
Gobierno de España. PSI2009–10341Editor's Version
http://dx.doi.org/10.1017/sjp.2014.50Subjects
Computerized adaptive testing; Ítem exposure control; Test security; Stratified methods; PsicologíaRights
© Universidad Complutense de Madrid and Colegio Oficial de Psicólogos de MadridAbstract
Test security can be a major problem in computerized adaptive testing, as examinees can share information about the items they receive. Of the different item selection rules proposed to alleviate this risk, stratified methods are among those that have received most attention. In these methods, only low discriminative items can be presented at the
beginning of the test and the mean information of the items increases as the test goes on. To do so, the item bank must be divided into several strata according to the information of the items. To date, there is no clear guidance about the optimal number of strata into which the item bank should be split. In this study, we will simulate conditions with different numbers of strata, from 1 (no stratification) to a number of strata equal to test length (maximum level of stratification) while manipulating the maximum exposure rate that no item should surpass (rmax) in its whole domain. In this way, we can plot the relation between test security and accuracy, making it possible to determine the number of
strata that leads to better security while holding constant measurement accuracy. Our data indicates that the best option is to stratify into as many strata as possible.
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Google Scholar:Barrada, Juan Ramón
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Abad García, Francisco José
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Olea Díaz, Julio
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