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Ligtvoet, Rudy

Models and methods for invariant item ordering

Rudy Ligtvoet (AiO)

Department of Methodology, Room S 109
Faculty of Social Sciences, Tilburg University
P.O. Box 90153
5000 LE Tilburg
Phone: +31 13 466 2089 / 2544 (secretary)
E-mail: Rudy Ligtvoet

Supervisors: Prof. dr K. Sijtsma, prof. dr J.K. Vermunt, dr A. Van der Ark
Project running from: 1 January 2006 – 1 January 2010

Summary

Items in a test or a questionnaire have an invariant item ordening (IIO) if the items have an identical ordering according to difficulty or atractiveness for every individual in the population of interest, with the exeption of possible ties. Several applications of test results require an IIO. Examples are the investigation of developmental theories, differential item functioning, aberrant response patterns, and the use of starting and stopping rules in administration. This PhD project proposal contains four parts, each investigating different aspects of the ordering of polytomous items in a test or questionnaire. The first project aims at the development of an item response theory model, which implies an invariant item ordering of polytomous items, which implies an invariant ordering. The psychometric properties of these models will be investigated. Second, methods for testing the invariant ordering of polytomous items, which have not yet been investigated thoroughly, are further developed and compared. Third, the use of latent class analysis as a tool for estimating item orderings is explored. Fourth, the newly developed models and methods are applied in the real data.

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