The Impact of Missing Data on the Detection of Nonuniform Differential Item Functioning

Abstract

Missing information is a ubiquitous aspect of data analysis, including responses to items on cognitive and affective instruments. Although the broader statistical literature describes missing data methods, relatively little work has focused on this issue in the context of differential item functioning (DIF) detection. Such prior research has focused on uniform DIF and has identified a complicated relationship between the type and amount of missing data, along with the methods for dealing with it. The current simulation study was designed to extend this earlier work by focusing on the impact of missing data and methods for dealing with it on nonuniform DIF detection using popular tools, including logistic regression, crossing SIBTEST, and the item response theory likelihood ratio test. Results suggest that the relationships between the various factors manipulated here were complex with no one method emerging as optimal in all cases, although listwise deletion consistently produced results similar to those obtained with the complete data across simulated conditions. Implications of these results are also discussed.