1. Department of Statistical Science, University College London, Gower Street, London WC1E 6BT, UK panagiota.filippou.12@ucl.ac.uk
2. Department of Statistical Science, University College London, Gower Street, London WC1E 6BT, UK
3. Department of Economics, Mathematics and Statistics, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK