1. Department of Social and Political Sciences, Bocconi University , Milano , Italy
2. Department of Public Health and Primary Care, University of Cambridge , Cambridge , UK
3. Department of Sociology, University of Cambridge , Cambridge , UK
4. Department of Sociology and Nuffield College, Leverhulme Centre for Demographic Science, Oxford University , Oxford , UK
5. Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine , London , UK
6. Department of Economics, University of Massachusetts Amherst , Amherst, MA , USA