Expetise: Methodology of Psychological and Social Sciences Research. Current research topics are: • Cross cultural comparability of subjective Qualitiy of Life experience: Measurement invariance in Quality of Life • Applications of Functional Measurement to Quality of life ratings • Applicability of the Anamnestic Comparative Self-Assessment (ACSA) scale for Quality of Life assessment • Data quality in websurveys : Context Effects in Surveys Other interests: • Measurement quality obtained from rating scales in surveys: the impact of scale anchoring, labels, orientation, dimensionality etc. • Electronic learning environments for education, specifically in the fields of mathematics, statistics, and methodological education. • Ordinal data-analysis (Boolean analysis) and mathematical modeling of work-related social processes. • Self-anchoring rating scales • Response effects and rating scale formats