1. Ph.D. Candidate, Dept. of Technology Management and Economics, Chalmers Univ. of Technology, SE-412 96 Gothenburg, Sweden. E-mail: fredrik.waara@chalmers.se
2. Professor, Dept. of Technology Management and Economics, Chalmers Univ. of Technology, SE-412 96 Gothenburg, Sweden. E-mail: jan.brochner@chalmers.se