Research: My primary interest are the methodological aspects of measurement by means of tests or questionnaires. Within this context my research can be divided into four themes: (1) finding methodological solutions to practical data problems, such as handling missing data, handling outliers, and item selection; (2) reliability of test data; (3) development of nonparametric item response theory models, including Mokken scale analysis; and (4) the development of categorical marginal models and their application to test data. For all themes, software development (in R) is an important aspect. In addition, I have made methodological and statistical contributions to substantive papers from various areas in the social and behavioral sciences.
Teaching: I have taught courses in methods and statistics at all levels between pre-Bachelor level and post-master level. My primary interest is raise methodological and statistical awareness in students,
Administration: As director of the Graduate School of Child Development and Education, my primary interest is to keep the master programmes and PhD programmes of Pedagogical Sciences, Educational Sciences, and the Interfaculty Teacher Training Programmes (ILO) in good shape in terms of quality, financial solvency, and working environment.