1. Department of Statistics, University of Oxford, OX1 3LB, Oxford, United Kingdom
2. Department of Mathematics and Statistics, University of Lancaster, LA1 4YF, Lancaster, United Kingdom
3. Department of Economics, Management and Statistics, University of Milano – Bicocca, 20126, Milano, Italy
4. Department of Economics and Statistics, University of Torino and Collegio Carlo Alberto, 10134, Torino, Italy