1. Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa
2. Faculty of Health Sciences, Department of Human Biology, Division of Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa;
3. Carnegie Applied Rugby Research (CARR) centre, Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK
4. Centre for Research into Ecological and Environmental Modelling, University of St Andrews, Saint Andrews, UK