1. INCHER and Institute of Economics, University of Kassel , Moenchebergstrasse 17, Kassel 34109, Germany . e-mail: buenstorf@uni-kassel.de
2. Economics Group, WHU—Otto Beisheim School of Management , Burgplatz 2, Vallendar 56179, Germany . e-mail: christina.guenther@whu.edu
3. Department of Economics, Friedrich Schiller University Jena , Carl-Zeiss-Strasse 3, Jena, Thüringen 07743, Germany . e-mail: sebastian.wilfling@yahoo.de