The Use of Angoff’s Transformed Item Difficulties Method in Detecting Differential Item Functioning

Year 2025, Volume: 25 Issue: 1, 398 - 424

Metehan Güngör , Ergul Demir

https://doi.org/10.17240/aibuefd.2025.25.90529-1441270

Abstract

In this study, the Angoff’s Transformed Item Difficulties method of detecting differential item functioning (DIF) is introduced with its important details and criticized aspects. The strengths and weaknesses of this Method are discussed. Among the pioneering methods developed for DIF detection in tests consisting of single-dimension items scored on a 0-1 scale, there are some criticisms in the literature regarding Angoff's Method. It is suggested that this Method may not be used due to criticisms such as its exclusive focus on item difficulties and the possibility of viewing real differences between groups as item bias. On the other hand, the Method has practical advantages such as ease of application, the possibility of graphical interpretation, and usability in relatively small samples. Within the scope of this study, the algorithm, general characteristics, strengths, and limitations of Angoff's Method are discussed. In addition, the step-by-step command lines for using Angoff's Method in DIF analysis with the "difR" package in the R programming language are explained. The discussions conducted indicate that using Angoff's Method for DIF detection comes with some important limitations that need to be taken into account. However, the Method's ease of application and visualization capabilities can be beneficial in explaining the fundamentals of bias and DIF concepts. This Method can provide more meaningful results when the test score averages of groups are close or equal in terms of the measured characteristics. The Method's limited use can be considered for the purpose of identifying potentially biased items in a test.

Keywords

Differential Item Functioning, Transformed Item Difficulties, Difr, Delta Plot, DIF Analysis.

Angoff’un Dönüştürülmüş Madde Güçlükleri Yöntemi’nin Değişen Madde Fonksiyonu Belirlemede Kullanımı

Abstract

Bu çalışmada değişen madde fonksiyonu (DMF) belirleme yöntemlerinden Angoff’un Dönüştürülmüş Madde Güçlükleri (Transformed Item Difficulties) Yöntemi önemli ayrıntıları ve eleştirilen yönleriyle tanıtılmakta, yöntemin güçlü ve zayıf yönleri tartışılmaktadır. Tek boyutlu ve 0-1 şeklinde puanlanan maddelerden oluşan testlerde DMF belirleme çalışmalarında kullanılmak üzere geliştirilmiş öncü yöntemlerden biri olan Angoff’un yöntemine yönelik olarak alan yazında bazı eleştiriler bulunmaktadır. Yöntemin yalnızca madde güçlüklerine odaklı olması, gruplar arasındaki gerçek farkın değişen madde fonksiyonu olarak görülme olasılığı bulunması gibi nedenlerle bu yöntemin kullanılmaması önerilebilmektedir. Diğer taraftan yöntem, uygulama kolaylığı, grafiksel yorumlama imkânı tanıması ve görece küçük örneklemlerde de kullanılabilmesi gibi pratik avantajlara sahiptir. Bu kapsamda bu çalışmada Angoff’un yönteminin algoritması, genel karakteristiği, güçlü yönleri ve sınırlılıkları tartışılmıştır. Ayrıca, R programlama dili üzerinde kullanılabilen “difR” paketi ile DMF analizinde Angoff’un yönteminin nasıl kullanılacağı adım adım satır komutları yardımıyla açıklanmıştır. Yürütülen tartışmalar göstermektedir ki, Angoff’un Yöntemi ile DMF belirleme, dikkat edilmesi gereken bazı önemli sınırlılıklar içermektedir. Bununla birlikte yöntemin uygulama kolaylığı ve görselleştirme imkânı tanıyor oluşu, yanlılık ve DMF kavramlarının temellerinin açıklanması açısından yararlı olabilir. Bu yöntem, grupların ölçülen özellik bakımından test puanı ortalamalarının yakın ya da eşit olması durumunda daha anlamlı sonuçlar verebilmektedir. Yöntemin, bir testteki potansiyel olarak yanlı maddelerin belirlenmesinde bir öngörü sağlaması amacıyla daha sınırlı kullanımı düşünülebilir.

Keywords

Değişen Madde Fonksiyonu, Dönüştürülmüş Madde Güçlükleri, Difr, Delta Yöntemi, DMF Analizi

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