Eike B. Kroll Otto-von-Guericke-University Magdeburg   Universitaetsplatz 2 P.O. Box 4120 Magdeburg, 39106 Germany   eike.kroll@ovgu.de   www.emwifo.ovgu.de           JEL Areas: C9 : Design of Experiments: General D8 : Information, Knowledge, and Uncertainty: General