Dr. Matthias von Davier is principal research scientist in the Research & Development Division at Educational Testing Service. He joined ETS, which is located in Princeton, NJ, USA, in 2000. He earned his Ph.D. in psychology from University of Kiel, Germany, in 1996, specializing in psychometrics. Von Davier advises the method group of competency tests on IRT-scaling (in particular software, modeling and linking).