DIF Assessment for Polytomously Scored Items: A Framework for Classification and Evaluation

Abstract

Increased use of alternatives to the traditional dichotomously
\nscored multiple-choice item yield complex
\nresponses that require complex scoring rules.
\nSome of these new item types can be polytomously
\nscored. DIF methodology is well-defined for traditional
\ndichotomously scored multiple-choice items.
\nThis paper provides a classification scheme of DIF
\nprocedures for dichotomously scored items that is
\napplicable to new DIF procedures for polytomously
\nscored items. In the process, a formal development of
\na polytomous version of a dichotomous DIF technique
\nis presented. Several polytomous DIF techniques are
\nevaluated in terms of statistical and practical
\ncriteria. Index terms: DIF methodology, differential
\nitem functioning, item bias, polytomous scoring, statistical
\ncriteria for differential item functioning.