Sample interview questions: Can you explain the concept of differential item functioning (DIF) and how it is assessed in practice?
Sample answer:
Differential item functioning (DIF) is a crucial concept in psychometrics that refers to the situation where an item on a test or questionnaire functions differently for different groups of individuals, despite having similar levels of the latent trait being measured. In simpler terms, DIF occurs when an item is easier or more difficult for one group compared to another, even if they possess the same level of ability or trait.
To assess DIF in practice, several statistical methods are commonly used. One widely used method is the item response theory (IRT) approach, specifically the logistic regression-based approach known as the Mantel-Haenszel method. This method compares the item response probabilities between different groups while controlling for the latent trait being measured. It allows for the identification of DIF by evaluating whether the relationship between item responses and the latent trait differs across groups.
Another commonly used method to assess DIF is the differential test functioning (DTF) approach. DTF involves comparing the performance of different groups on the test a… Read full answer