Recent advances in analysis of differential item functioning in health research using the Rasch model

Abstract Background Rasch analysis with a focus on Differential Item Functioning (DIF) is increasingly used for examination of psychometric properties of health outcome measures. To take account of DIF in order to retain precision of measurement, split of DIF-items into separate sample specific item...

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Main Authors: Curt Hagquist, David Andrich
Format: Article
Language:English
Published: BMC 2017-09-01
Series:Health and Quality of Life Outcomes
Subjects:
Online Access:http://link.springer.com/article/10.1186/s12955-017-0755-0
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author Curt Hagquist
David Andrich
author_facet Curt Hagquist
David Andrich
author_sort Curt Hagquist
collection DOAJ
description Abstract Background Rasch analysis with a focus on Differential Item Functioning (DIF) is increasingly used for examination of psychometric properties of health outcome measures. To take account of DIF in order to retain precision of measurement, split of DIF-items into separate sample specific items has become a frequently used technique. The purpose of the paper is to present and summarise recent advances of analysis of DIF in a unified methodology. In particular, the paper focuses on the use of analysis of variance (ANOVA) as a method to simultaneously detect uniform and non-uniform DIF, the need to distinguish between real and artificial DIF and the trade-off between reliability and validity. An illustrative example from health research is used to demonstrate how DIF, in this case between genders, can be identified, quantified and under specific circumstances accounted for using the Rasch model. Methods Rasch analyses of DIF were conducted of a composite measure of psychosomatic problems using Swedish data from the Health Behaviour in School-aged Children study for grade 9 students collected during the 1985–2014 time periods. Results The procedures demonstrate how DIF can be identified efficiently by ANOVA of residuals, and how the magnitude of DIF can be quantified and potentially accounted for by resolving items according to identifiable groups and using principles of test equating on the resolved items. The results of the analysis also show that the real DIF in some items does affect person measurement estimates. Conclusions Firstly, in order to distinguish between real and artificial DIF, the items showing DIF initially should not be resolved simultaneously but sequentially. Secondly, while resolving instead of deleting a DIF item may retain reliability, both options may affect the content validity negatively. Resolving items with DIF is not justified if the source of the DIF is relevant for the content of the variable; then resolving DIF may deteriorate the validity of the instrument. Generally, decisions on resolving items to deal with DIF should also rely on external information.
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spelling doaj.art-f6aaed7b73624353a95d6817cf2a7d1c2022-12-22T02:17:37ZengBMCHealth and Quality of Life Outcomes1477-75252017-09-011511810.1186/s12955-017-0755-0Recent advances in analysis of differential item functioning in health research using the Rasch modelCurt Hagquist0David Andrich1Centre for Research on Child and Adolescent Mental Health, Karlstad UniversityGraduate School of Education, The University of Western AustraliaAbstract Background Rasch analysis with a focus on Differential Item Functioning (DIF) is increasingly used for examination of psychometric properties of health outcome measures. To take account of DIF in order to retain precision of measurement, split of DIF-items into separate sample specific items has become a frequently used technique. The purpose of the paper is to present and summarise recent advances of analysis of DIF in a unified methodology. In particular, the paper focuses on the use of analysis of variance (ANOVA) as a method to simultaneously detect uniform and non-uniform DIF, the need to distinguish between real and artificial DIF and the trade-off between reliability and validity. An illustrative example from health research is used to demonstrate how DIF, in this case between genders, can be identified, quantified and under specific circumstances accounted for using the Rasch model. Methods Rasch analyses of DIF were conducted of a composite measure of psychosomatic problems using Swedish data from the Health Behaviour in School-aged Children study for grade 9 students collected during the 1985–2014 time periods. Results The procedures demonstrate how DIF can be identified efficiently by ANOVA of residuals, and how the magnitude of DIF can be quantified and potentially accounted for by resolving items according to identifiable groups and using principles of test equating on the resolved items. The results of the analysis also show that the real DIF in some items does affect person measurement estimates. Conclusions Firstly, in order to distinguish between real and artificial DIF, the items showing DIF initially should not be resolved simultaneously but sequentially. Secondly, while resolving instead of deleting a DIF item may retain reliability, both options may affect the content validity negatively. Resolving items with DIF is not justified if the source of the DIF is relevant for the content of the variable; then resolving DIF may deteriorate the validity of the instrument. Generally, decisions on resolving items to deal with DIF should also rely on external information.http://link.springer.com/article/10.1186/s12955-017-0755-0Analysis of varianceDifferential Item Functioning (DIF)HealthRaschReal and artificial DIFValidity and reliability
spellingShingle Curt Hagquist
David Andrich
Recent advances in analysis of differential item functioning in health research using the Rasch model
Health and Quality of Life Outcomes
Analysis of variance
Differential Item Functioning (DIF)
Health
Rasch
Real and artificial DIF
Validity and reliability
title Recent advances in analysis of differential item functioning in health research using the Rasch model
title_full Recent advances in analysis of differential item functioning in health research using the Rasch model
title_fullStr Recent advances in analysis of differential item functioning in health research using the Rasch model
title_full_unstemmed Recent advances in analysis of differential item functioning in health research using the Rasch model
title_short Recent advances in analysis of differential item functioning in health research using the Rasch model
title_sort recent advances in analysis of differential item functioning in health research using the rasch model
topic Analysis of variance
Differential Item Functioning (DIF)
Health
Rasch
Real and artificial DIF
Validity and reliability
url http://link.springer.com/article/10.1186/s12955-017-0755-0
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