[1] Univ Utrecht, Dept Econ Geog, NL-3584 CS Utrecht, Netherlands
[2] Katholieke Univ Leuven, Dept Managerial Econ Strategy & Innovat, B-3000 Louvain, Belgium
[3] TU Dortmund, Fac Econ, Dept Econ, D-44227 Dortmund, Germany
[4] Katholieke Univ Leuven, Ctr R&D Monitoring ECOOM, B-3000 Louvain, Belgium
[5] Ctr European Econ Res ZEW, Mannheim, Germany