1. Department of Business Administration and Economics; Bielefeld University; Bielefeld 33615 Germany
2. Department of Statistics; Iowa State University; Ames 50011 IA USA
3. Centre for Research into Ecological and Environmental Modelling; University of St Andrews; St Andrews KY16 9LZ Fife UK
4. School of Environment, Arts and Society; Florida International University; North Miami 33181 FL USA