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Statistical Tests of Conditional Independence Between Responses and/or Response Times on Test Items

Published online by Cambridge University Press:  01 January 2025

Wim J. van der Linden and
Cees A. W. Glas
Wim J. van der Linden*
Affiliation:
University of Twente and CTB/McGraw-Hill
Cees A. W. Glas
Affiliation:
University of Twente
*
Requests for reprints should be sent to Wim J. van der Linden, CTB/McGraw-Hill, 20 Ryan Ranch Road, Monterey, CA 93940, USA. E-mail: wim_vanderlinden@ctb.com
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Abstract

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Three plausible assumptions of conditional independence in a hierarchical model for responses and response times on test items are identified. For each of the assumptions, a Lagrange multiplier test of the null hypothesis of conditional independence against a parametric alternative is derived. The tests have closed-form statistics that are easy to calculate from the standard estimates of the person parameters in the model. In addition, simple closed-form estimators of the parameters under the alternatives of conditional dependence are presented, which can be used to explore model modification. The tests were applied to a data set from a large-scale computerized exam and showed excellent power to detect even minor violations of conditional independence.

Keywords

conditional independenceitem-response theory (IRT)hierarchical modelingLagrange multiplier testslognormal modelresponse time

Information

Type
Theory and Methods
Information
Psychometrika , Volume 75 , Issue 1 , March 2010, pp. 120 - 139
Creative Commons
Creative Common License - CCCreative Common License - BYCreative Common License - NC
This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Copyright
Copyright © 2009 The Psychometric Society

Footnotes

This study received funding from the Law School Admissions Council (LSAC). The opinions and conclusions contained in this paper are those of the author and do not necessarily reflect the policy and position of LSAC.

Wim J. van der Linden is now at CTB/McGraw-Hill.

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