1. Department of Economics, Poole College of Management, North Carolina State University , Raleigh, NC 27695-8110, USA
2. CREATES, Department of Economics and Business Economics, Aarhus University, Fuglesangs Allé 4, Aarhus V 8210, Denmark
3. Department of Econometrics and Business Statistics, Monash University, Caulfield East, VIC 3145, Australia