David Thissen, University of North Carolina at Chapel Hill
A Selective Intellectual History of Differential Item Functioning Analysis in Item Response Theory and Factorial Invariance in Factor Analysis
2024 Career Award for Lifetime Achievement
The concept of factorial invariance has evolved since it originated in the 1930s as a criterion for the usefulness of the multiple factor model; it has become a form of analysis supporting the validity of inferences about group differences on underlying latent variables. The analysis of differential item functioning (DIF) arose in the literature of item response theory (IRT), where its original purpose was the detection and removal of test items that are differentially difficult for, or biased against, one subpopulation or another. The two traditions merge at the level of the underlying latent variable model, but their separate origins and different purposes have led them to differ in details of terminology and procedure. This review traces some aspects of the histories of the two traditions, ultimately drawing some conclusions about how analysts may draw on elements of both, and how the nature of the research question determines the procedures used. Whether statistical tests are grouped by parameter (as in studies of factorial invariance) or across parameters by variable (as in DIF analysis) depends on the context and is independent of the model, as are subtle aspects of the order of the tests. In any case in which DIF or partial invariance is a possibility, the invariant parameters, or anchor items in DIF analysis, are best selected in an interplay between the statistics and judgment about what is being measured.
About the Speaker
David Thissen is Professor Emeritus in the Department of Psychology and Neuroscience at the University of North Carolina at Chapel Hill, after thirty years on the faculty there following fourteen years at the University of Kansas. He did his graduate work at the University of Chicago, where he received his PhD in 1976. His primary research interests have involved statistical models and methods for psychological and educational measurement. He has been author or co-author of more than 200 articles and chapters and several books on a variety of topics about and using quantitative methods in psychology and other sciences. During his faculty career, Thissen was primary advisor for a dozen and a half Ph.D. students. He has been active with the Psychometric Society for fifty years, serving at times on its editorial council, the board of trustees, and as its president (2000-2001). He has been, and continues to be, a member of technical advisory committees for a number of state and national testing programs. At present he writes and continues to serve on the committees of graduate students in quantitative psychology.