First Author:   Clemens Puppe University of Bonn clemens.puppe@econ3.uni-bonn.de   Department of Economics, University of Bonn, Adenauerallee 24-42 Bonn, D - 53113, Germany   +49 228 735747(Phone) +49 228 735747(Fax) Second Author: Rudolf Kerschbamer University of Vienna rudolf.kerschbamer@univie.ac.at   Department of Economics, University of Vienna, Hohenstaufengasse 9 Vienna, A - 1010, Austria   +43 1 4277-37429(Phone) +43 1 4277-9374(Fax)