title: Monitoring Countries in a Changing World: A New Look at DIF in International Surveys.
abstract: This paper discusses the issue of differential item functioning (DIF) in international surveys. DIF is likely to occur in international surveys. What is needed is a statistical approach that takes DIF into account, while at the same time allowing for meaningful comparisons between countries. Some existing approaches are discussed and an alternative is provided. The core of this alternative approach is to define the construct as a large set of items, and to report in terms of summary statistics. Since the data are incomplete, measurement models are used to complete the incomplete data. For that purpose, different models can be used across countries. The method is illustrated with PISA's reading literacy data. The results indicate that this approach fits the data better than the current PISA methodology; however, the league tables are nearly identical. The implications for monitoring changes over time are discussed.
authors.affiliation: University of Amsterdam, Amsterdam, The Netherlands. zwitser@uva.nl.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Zwitser
authors.affiliation: University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: S Sjoerd F
authors.initials: SS
authors.lastname: Glaser
authors.affiliation: University of Amsterdam, Amsterdam, The Netherlands.|Cito Institute for Educational Measurement, Arnhem, The Netherlands.
authors.forename: Gunter
authors.initials: G
authors.lastname: Maris
mesh_terms: D002170:Canada; D004521:Educational Measurement; D006801:Humans; D038622:Internationality; D000067010:Literacy; D008800:Mexico; D015233:Models, Statistical; D011594:Psychometrics; D011932:Reading; D011795:Surveys and Questionnaires
keywords: DIF; PISA; Rasch models; differential item functioning; educational testing; programme for international student assessment; ranking; reading literacy; robustness