1. Centre for Public Health Research, Massey University, Wellington, New Zealand
2. School of Fundamental Sciences—Statistics, College of Sciences, Massey University, Palmerston North, New Zealand
3. Research School of Finance, Actuarial Studies and Statistics, The Australian National University, Canberra, Australian National Territory, Australia
4. Section of Epidemiology and Biostatistics, School of Population Health, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand