1. Department of Mathematics, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany and Department of Mathematics and Computer Science, Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands
2. Department of Mathematics, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
3. Statistical Methodology, Novartis Pharma AG, CH-4002 Basel, Switzerland