1. School of Mathematical and Physical Sciences, University of Newcastle, NSW 2308, Australia
2. National Institute for Applied Statistics Research Australia (NIASRA), School of Mathematics and Applied Statistics, University of Wollongong, Wollongong, NSW 2522, Australia
3. Department of Mathematical Modelling, Statistics and Bioinformatics, Ghent University, Coupure Links 653, 9000 Gent, Belgium